虽然是古老的问题，最近用到这个，查一下还不少东东呐
一、使用Environment.SpecialFolder
该方法最简单，直接使用即可，只是提供的特殊路径比较少。
(1)使用方法：
string path = Environment.GetFolderPath(Environment.SpecialFolder.Programs);
(2)获取参数：
foreach (Environment.SpecialFolder s in
Enum.GetValues(typeof(Environment.SpecialFolder)))
{
Console.WriteLine("{0} folder : {1}",
s, Environment.GetFolderPath(s));
}
(3)输出参数列表：
Desktop = C:\Documents and Settings\gmj\桌面
Programs = C:\Documents and Settings\gmj\「开始」菜单\程序
Personal = E:\我的文档
Personal = E:\我的文档
Favorites = C:\Documents and Settings\gmj\Favorites
Startup = C:\Documents and Settings\gmj\「开始」菜单\程序\启动
Recent = C:\Documents and Settings\gmj\Recent
SendTo = C:\Documents and Settings\gmj\SendTo
StartMenu = C:\Documents and Settings\gmj\「开始」菜单
MyMusic = E:\我的文档\My Music
DesktopDirectory = C:\Documents and Settings\gmj\桌面
MyComputer =
Templates = C:\Documents and Settings\gmj\Templates
ApplicationData = C:\Documents and Settings\gmj\Application Data
LocalApplicationData = C:\Documents and Settings\gmj\Local Settings\Application Data
InternetCache = C:\Documents and Settings\gmj\Local Settings\Temporary Internet Files
Cookies = C:\Documents and Settings\gmj\Cookies
History = C:\Documents and Settings\gmj\Local Settings\History
CommonApplicationData = C:\Documents and Settings\All Users\Application Data
System = C:\WINDOWS\system32
ProgramFiles = C:\Program Files
MyPictures = E:\我的文档\My Pictures
CommonProgramFiles = C:\Program Files\Common Files
合计：23行
二、使用Environment.GetEnvironmentVariable
该方法可提供更多内容。
(1)使用方法：
string path = Environment.GetEnvironmentVariable("ALLUSERSPROFILE");
(2)获取参数：
foreach (DictionaryEntry de in Environment.GetEnvironmentVariables())
{
Console.WriteLine(" {0} = {1}", de.Key, de.Value);
}
(3)输出参数列表：
Path = D:\Program Files\Sun\OPhone SDK\tools;D:\Program Files\Sun\android-sdk-windows-1.5_r2\tools;D:\Program
Files\Sun\SDK\jdk\bin;D:\Program Files\Sun\SDK\jdk\jre\bin;E:\oracle\ora92\bin;C:\Program Files\Oracle\jre\1.3.1\bin;C:\Program
Files\Oracle\jre\1.1.8\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\Program Files\Intel\DMIX;C:\Program
Files\Microsoft SQL Server\90\Tools\binn\;D:\Program Files\CodeSmith\v5.0\;D:\Program Files\Symantec\pcAnywhere\;C:\Program
Files\Ixia\IxChariot;D:\Program Files\Sun\SDK\bin;
TEMP = C:\DOCUME~1\gmj\LOCALS~1\Temp
SESSIONNAME = Console
PATHEXT = .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH
USERDOMAIN = EVER62
PROCESSOR_ARCHITECTURE = x86
SystemDrive = C:
APPDATA = C:\Documents and Settings\gmj\Application Data
JSERV = E:\oracle\ora92/Apache/Jserv/conf
windir = C:\WINDOWS
_ACP_INCLUDE = D:\Program Files\Microsoft Visual Studio 8\VC\include;D:\Program Files\Microsoft Visual Studio 8
\VC\atlmfc\include;D:\Program Files\Microsoft Visual Studio 8\VC\PlatformSDK\include;D:\Program Files\Microsoft Visual Studio 8
\SDK\v2.0\include
TMP = C:\DOCUME~1\gmj\LOCALS~1\Temp
USERPROFILE = C:\Documents and Settings\gmj
ProgramFiles = C:\Program Files
FP_NO_HOST_CHECK = NO
HOMEPATH = \Documents and Settings\gmj
COMPUTERNAME = EVER62
_ACP_PATH = D:\Program Files\Microsoft Visual Studio 8\VC\bin;D:\Program Files\Microsoft Visual Studio 8
\VC\PlatformSDK\bin;D:\Program Files\Microsoft Visual Studio 8\Common7\Tools\bin;D:\Program Files\Microsoft Visual Studio 8
\Common7\tools;D:\Program Files\Microsoft Visual Studio 8\Common7\ide;C:\Program Files\HTML Help Workshop;D:\Program
Files\Microsoft Visual Studio 8\SDK\v2.0\bin;C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727;D:\Program Files\Microsoft Visual
Studio 8\;D:\Program Files\Microsoft Visual Studio 8\\SDK\v2.0\bin;C:\WINDOWS\SysWow64;D:\Program Files\Microsoft Visual Studio
8\Team Tools\Static Analysis Tools\FxCop\;D:\Program Files\Sun\OPhone SDK\tools;D:\Program Files\Sun\android-sdk-windows-1.5_r2
\tools;D:\Program Files\Sun\SDK\jdk\bin;D:\Program Files\Sun\SDK\jdk\jre\bin;E:\oracle\ora92\bin;C:\Program
Files\Oracle\jre\1.3.1\bin;C:\Program Files\Oracle\jre\1.1.8\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32
\Wbem;C:\Program Files\Intel\DMIX;C:\Program Files\Microsoft SQL Server\90\Tools\binn\;D:\Program Files\CodeSmith\v5.0
\;D:\Program Files\Symantec\pcAnywhere\;C:\Program Files\Ixia\IxChariot;D:\Program Files\Sun\SDK\bin;
USERNAME = gmj
NUMBER_OF_PROCESSORS = 2
PROCESSOR_IDENTIFIER = x86 Family 6 Model 23 Stepping 6, GenuineIntel
_ACP_LIB = D:\Program Files\Microsoft Visual Studio 8\VC\lib;D:\Program Files\Microsoft Visual Studio 8
\VC\atlmfc\lib;D:\Program Files\Microsoft Visual Studio 8\VC\atlmfc\lib\i386;D:\Program Files\Microsoft Visual Studio 8
\VC\PlatformSDK\lib;D:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\lib;D:\Program Files\Microsoft Visual Studio 8
\;D:\Program Files\Microsoft Visual Studio 8\lib
WecVersionForRosebud.DA8 = 2
SystemRoot = C:\WINDOWS
ComSpec = C:\WINDOWS\system32\cmd.exe
LOGONSERVER = http://www.cnblogs.com/xinyuxin912/***
VS80COMNTOOLS = D:\Program Files\Microsoft Visual Studio 8\Common7\Tools\
_ACP_ATLPROV = D:\Program Files\Microsoft Visual Studio 8\VC\Bin\ATLProv.dll
WV_GATEWAY_CFG = E:\oracle\ora92\Apache\modplsql\cfg\wdbsvr.app
CommonProgramFiles = C:\Program Files\Common Files
PROCESSOR_LEVEL = 6
PROCESSOR_REVISION = 1706
CLIENTNAME = Console
ALLUSERSPROFILE = C:\Documents and Settings\All Users
VS90COMNTOOLS = D:\Program Files\Microsoft Visual Studio 9.0\Common7\Tools\
OS = Windows_NT
HOMEDRIVE = C:
合计：37行
三、调用shell32中的SHGetSpecialFolderPath
需要引用"System.Runtime.InteropServices”命名空间。
(1)使用方法：
[DllImport("shell32.dll")]
static extern bool SHGetSpecialFolderPath(IntPtr hwndOwner,[Out] StringBuilder lpszPath, int nFolder, bool fCreate);
const int CSIDL_PROGRAMS = 2; // \Windows\Start Menu\Programs
StringBuilder pathBuilder = new StringBuilder(260);
SHGetSpecialFolderPath(IntPtr.Zero, pathBuilder, CSIDL_PROGRAMS, false);
string path = pathBuilder.ToString(); // should now hold the path
(2)参数列表：
Here's the full list of CSIDL's from ShlObj.h
const int CSIDL_DESKTOP = 0x0000; // <desktop>
const int CSIDL_INTERNET = 0x0001; // Internet Explorer (icon on desktop)
const int CSIDL_PROGRAMS = 0x0002; // Start Menu\Programs
const int CSIDL_CONTROLS = 0x0003; // My Computer\Control Panel
const int CSIDL_PRINTERS = 0x0004; // My Computer\Printers
const int CSIDL_PERSONAL = 0x0005; // My Documents
const int CSIDL_FAVORITES = 0x0006; // <user name>\Favorites
const int CSIDL_STARTUP = 0x0007; // Start Menu\Programs\Startup
const int CSIDL_RECENT = 0x0008; // <user name>\Recent
const int CSIDL_SENDTO = 0x0009; // <user name>\SendTo
const int CSIDL_BITBUCKET = 0x000a; // <desktop>\Recycle Bin
const int CSIDL_STARTMENU = 0x000b; // <user name>\Start Menu
const int CSIDL_MYDOCUMENTS = CSIDL_PERSONAL; // Personal was just a silly name for My Documents
const int CSIDL_MYMUSIC = 0x000d; // "My Music" folder
const int CSIDL_MYVIDEO = 0x000e; // "My Videos" folder
const int CSIDL_DESKTOPDIRECTORY = 0x0010; // <user name>\Desktop
const int CSIDL_DRIVES = 0x0011; // My Computer
const int CSIDL_NETWORK = 0x0012; // Network Neighborhood (My Network Places)
const int CSIDL_NETHOOD = 0x0013; // <user name>\nethood
const int CSIDL_FONTS = 0x0014; // windows\fonts
const int CSIDL_TEMPLATES = 0x0015;
const int CSIDL_COMMON_STARTMENU = 0x0016; // All Users\Start Menu
const int CSIDL_COMMON_PROGRAMS = 0x0017; // All Users\Start Menu\Programs
const int CSIDL_COMMON_STARTUP = 0x0018; // All Users\Startup
const int CSIDL_COMMON_DESKTOPDIRECTORY = 0x0019; // All Users\Desktop
const int CSIDL_APPDATA = 0x001a; // <user name>\Application Data
const int CSIDL_PRINTHOOD = 0x001b; // <user name>\PrintHood
const int CSIDL_LOCAL_APPDATA = 0x001c; // <user name>\Local Settings\Applicaiton Data (non roaming)
const int CSIDL_ALTSTARTUP = 0x001d; // non localized startup
const int CSIDL_COMMON_ALTSTARTUP = 0x001e; // non localized common startup
const int CSIDL_COMMON_FAVORITES = 0x001f;
const int CSIDL_INTERNET_CACHE = 0x0020;
const int CSIDL_COOKIES = 0x0021;
const int CSIDL_HISTORY = 0x0022;
const int CSIDL_COMMON_APPDATA = 0x0023; // All Users\Application Data
const int CSIDL_WINDOWS = 0x0024; // GetWindowsDirectory()
const int CSIDL_SYSTEM = 0x0025; // GetSystemDirectory()
const int CSIDL_PROGRAM_FILES = 0x0026; // C:\Program Files
const int CSIDL_MYPICTURES = 0x0027; // C:\Program Files\My Pictures
const int CSIDL_PROFILE = 0x0028; // USERPROFILE
const int CSIDL_SYSTEMX86 = 0x0029; // x86 system directory on RISC
const int CSIDL_PROGRAM_FILESX86 = 0x002a; // x86 C:\Program Files on RISC
const int CSIDL_PROGRAM_FILES_COMMON = 0x002b; // C:\Program Files\Common
const int CSIDL_PROGRAM_FILES_COMMONX86 = 0x002c; // x86 Program Files\Common on RISC
const int CSIDL_COMMON_TEMPLATES = 0x002d; // All Users\Templates
const int CSIDL_COMMON_DOCUMENTS = 0x002e; // All Users\Documents
const int CSIDL_COMMON_ADMINTOOLS = 0x002f; // All Users\Start Menu\Programs\Administrative Tools
const int CSIDL_ADMINTOOLS = 0x0030; // <user name>\Start Menu\Programs\Administrative Tools
const int CSIDL_CONNECTIONS = 0x0031; // Network and Dial-up Connections
const int CSIDL_COMMON_MUSIC = 0x0035; // All Users\My Music
const int CSIDL_COMMON_PICTURES = 0x0036; // All Users\My Pictures
const int CSIDL_COMMON_VIDEO = 0x0037; // All Users\My Video
const int CSIDL_RESOURCES = 0x0038; // Resource Direcotry
const int CSIDL_RESOURCES_LOCALIZED = 0x0039; // Localized Resource Direcotry
const int CSIDL_COMMON_OEM_LINKS = 0x003a; // Links to All Users OEM specific apps
const int CSIDL_CDBURN_AREA = 0x003b; // USERPROFILE\Local Settings\Application Data\Microsoft\CD Burning
const int CSIDL_COMPUTERSNEARME = 0x003d; // Computers Near Me (computered from Workgroup membership)
const int CSIDL_FLAG_CREATE = 0x8000; // combine with CSIDL_ value to force folder creation in SHGetFolderPath()
const int CSIDL_FLAG_DONT_VERIFY = 0x4000; // combine with CSIDL_ value to return an unverified folder path
const int CSIDL_FLAG_DONT_UNEXPAND = 0x2000; // combine with CSIDL_ value to avoid unexpanding environment variables
const int CSIDL_FLAG_NO_ALIAS = 0x1000; // combine with CSIDL_ value to insure non-alias versions of the pidl
const int CSIDL_FLAG_PER_USER_INIT = 0x0800; // combine with CSIDL_ value to indicate per-user init (eg. upgrade)
四、期待.net4.0
还没装.net4.0呢，好像已经扩展了SpecialFolder，比如我要获取 "C:\Documents and Settings\All Users\「开始」菜单\程序",则可以直接使用
string path = Environment.GetFolderPath(Environment.SpecialFolder.CommonPrograms);
没实际验证过，如果您验证了帮我补充一下吧^_^