I'm surprised you didn't dual boot, Blue. While I'd never use a beta OS as my only OS, I do have XP x64 beta dual booted along with regular old XP. This way I can have an OS that will run all current programs, and an OS to experiment with that can run any 64-bit games/programs.
I've had reasonably good luck with XP x64. Again, it cannot fully replace XP yet, as your bound to find things that don't work with it (i.e. Doom 3, which has an unofficial hack/patch to get it to install under x64).
On the positive side, I've found 64-bit drivers for the important gaming parts of my system (nforce 3 drivers, audigy drivers, ATI drivers). No printing drivers, but I'm not using x64 to print. Additionally, I've had decent luck with games. Most interesting is that some games are being reported to run significantly faster on x64 (I personally noticed Joint Ops runs quite a bit smoother, which I got the idea to try after others were reporting similar improvements).
Anyway, I can't reccommend anyone use x64 as their main OS because it's highly likely some of your software/hardware won't work, but it is a fun secondary OS to play around with (just make sure you stick each OS on separate hard drives or partitions). Now if America's Army, Far Cry and UT2K4 would just hurry up and get 64-bit patches for x64....