Windows 2000 support has been discontinued and VC++ 2010 cannot compile applications that will run on Win2K. It's that simple. If you need to support Win2K, use the VS2010 Multi Targetting feature to let VC++2010 use the VC++2008 compilers and libraries.
See also the following Connect issue which is an official answer from Microsoft.
Take a look at one of my earlier posts in this thread. The latest VC++2010 compiler is putting 5.01 as subsystem version in the PE headers. Windows 2K does not understand that. To keep it running on Win2K, the version in the PE headers should be 5.00.