[link|http://support.microsoft.com/support/kb/articles/Q279/7/92.ASP|http://support.micr...279/7/92.ASP]

During the development of WinXP, they created a fairly large app compatability layer for WinXP, which they backported to Win2k and stuck in Win2k SP2. It's not enabled by default, but by doing the reghack listed above, it adds a compatability tab to your program's property page. Rather handy.