Setting vc++ directory is different with vs2008 on vs2010.
In vs2008, we can change our extensional directory by setting the environment directory by Tools->Options->Projects and Solutions->VC++ Directories.
In vs2010, this above setting is deprecated. You should change the extensional directories by using the properties of project(not solution).
Here is the steps for setting outside directories for your project.
1 choose the project you want to extend directories and see the properties windows below(if you don't change the windows layout).
2 Click the icon to call out the property page.
3 On the left navigator, Configuration Properties->VC++ Directories.
By the way, you will see you can change the former directories in "include directories". That causes that vs2010 will read the configuration file to set the reserved directories. So these directories will be unchanged. You should change the configuration file to change the reserved directory.
You can find the file under such path(Under windows 7 opration system), C:\Users\Account\AppData\Local\Microsoft\MSBuild\v4.0\Microsoft.Cpp.Win32.user.props
For windows xp platform, you can find the file under C:\Documents and Settings\UserName\Local Settings\Application Data\Microsoft\MSBuild\v4.0
Using text editor to open it and you will find the reserved directories apperantly.