You can use the "Windows SDK Configuration Tool" which gets installed with any SDK. When you start that tool, it shows you all the installed SDK's to choose from, and the one you choose is then used in VS2008.
PS : Check also "Windows SDK Configuration Tool May Report an Error When OS Display Format is not English" at http://blogs.msdn.com/b/windowssdk/archive/2009/08/21/windows-sdk-configuration-tool-may-report-an-error-when-os-display-format-is-not-english.aspx