3 free XP and Vista compatible games from Good Old Games.
This site has plenty of other pay for games ($6 on average).
All games have had DRM removed and been updated to run on XP and Vista.
The games also seem to play better with SMALLER screens (because some gaes have a maximum resoultion of 640x480 when that was all you could squeeze from a graphics card). Good for old school PC gamers on old school PCs?