Yes, totally agree on the games front. The Mac Mini wasn't built to play the newest games. The graphics card only has 32MB of RAM for goodness sake! The games bundled with it really are dire as well.
If, on the other hand, you want a first class operating system - OS X is one of the best around - on a par with or better in some areas then XP, then get a Mac Mini. If you want to do basic productivity tasks like surf the Internet then get the Mini. If you want to use the iLife suite of programs (iDVD, iMovie etc.) to edit your DVD's or Movies' or to create music then get a Mac Mini. And if you want a securer system then XP with fewer viruses, no spyware and better security then get a Mac Mini.
If, on the other hand, you want to play games then, sadly, steer well clear.