Not sure if this should be listed under Vista or under Gaming.

Today I downloaded a game that is suppose to be for Windows XP--even though I have Vista Home Premium 32Bit. I have played games on my Vista before by manually making a game compatible using the compatible tab--right clicking on the program and selecting the compatible tab. But when I right clicked on the game icon in my program's list and chose properties, there was no compatible tab listed. Am I doing something wrong, or does this just mean you can't make this XP game compatible with Windows Vista?
Thanks,