How to use Compatibility Mode in Windows XP
Windows XP has a neat little feature that will allow older programs to run with it. You can set the program to use compatibility mode from an older version of Windows. Even if you can't install the program because of Windows XP, the compatibility mode wizard will allow it to install and run using the compatibility mode of an earlier version of Windows.
Check out this link from Microsoft for more information:
http://www.microsoft.com/windowsxp/pro/using/howto/gethelp/appcompat.asp