Some Windows XP work well or even better on Windows 7.
While this is true, it is not the same for some games, most times due to hardware drivers not recognize properly by a game.
Thankfully there is: Virtual PC Consolehttp://www.microsoft.com/windows/virtual-pc/
You can download it and then RUN and Install XP (or whatever other OS)
inside this utility, Now you can run XP and install all games and programs that you want
to run on true XP mode.
HINT: I use this for Windows 98/95 games and no more sound or video issues with drivers on any of those games.