I just tried out the VMWare 6.5 beta and Wow! It's so great!
It's hot a new graphical installer, so it's really easy to use, and you don't need the crazy any-any update to get it to work, which is great.
The coolest part though, is the DX9 support. I was on the verge of formatting my machine back to XP because i couldn't get so many games to work, but now I'm firmly back in Ubuntu-land. I have just been playing Portal in my WinXP VM. Runs at 30-50FPS with all settings at High. Same goes for Warcraft 3, and I've yet to try anything else.
Definitely worth the download to check it out though!
(This is on a Pentium Dual-Core 1.6Ghz, 2Gb RAM, and a GeForce 8600GT-Fatal1ty. The VM is a single-processor with 512Mb RAM).