I'm no expert...
I haven't played with Parallels 2.x in a while, but AFAIK it uses different graphics drivers than a native install. I'd be surprised if VMWare or the GPL tools were different except in special circumstances. The GUI just isn't as responsive.
I think I downloaded VMWare Server years ago, but don't recall actually using it. I realize things have improved over time. I understand that it's not reasonable to expect that there is *no* overhead in using a hypervisor. I know things are improving, and I applaud the fact that even the free tools are very, very good.
I just wish that if, in a year, I spent $1500-$2000 on a 3.x GHz quad core system with 4-6 GB of RAM, then I could truly seamlessly run Linux, Win2k or XP, and OS X simultaneously on the same desktop. Even if Steve allowed it, I just don't think we're there yet.
It'll be fun to play with it on faster hardware. Maybe next year...
Cheers,
Scott.