Yeah, if all of your partitions are NTFS (or you only have one partition and it's NTFS), you're pretty much hosed.

If, however, you have a FAT partition (even if it's FAT32, I think), you could always pop your old DOS games on that partition and then make a boot disk for an old version of DOS...The OS could run on the floppy, and you'd just call the game from your hard drive.

But yeah, it's almost impossible to play old games in XP.