Moonshine, you can run DOS games through WindowsXP without problems with the games themselves...
However you will often come across Sound/Graphics Problems, simply because DOS games are trying to access area's of cards which sometimes no longer exist (ATi Radeon and Matrix Perhilia are good examples)
I will have to remember the links, but
VMMSound is the best Sound Blaster 16 Emulator, infact i use it with all my sound cards for dos games as even my SB16 (yeah i still have a real SB16) doesn't work with them anymore.
Lucasart games are well known for this Sound bug even since thier dos days.
(You can download the latest ScummVM from sourceforge for these games though and they'll run perfectly on Linux/Windows)
The second for Graphics is SCiTECH Display Doctor or Glidos.
SCiTECH is pretty famous and will allows your games to access the new addresses for the functionality it seeks, works on every game.
Glidos will wrapper any Glide based game to OpenGL, which is good for games like Carmageddon, MW2 for dos, etc...
Most games though like Alone in the Dark will work fine with std WindowsXP emulation. For some like Elite2 and X-Wing you will have to change the memory settings so that you have more than 600KB base.
AthlonXP 2500+ | 256MB DDR PC2700 | GeForce FX 5200 44.04 | DirectX 9.0 | Audigy2 | Crystal Clean OS