I'm probably going to stick with VMware server 2 now. I've got my various VMs to the point where I VNC or SSH into them directly so the web console now gets rarely used. Seems pretty rock solid and certainly zippy enough.

If I was going to do anything more involved then I'd probably go for 2 luke warm Poweredges and run ESXi on them with a 3rd box running OpenFiler. Virtual Box is pretty neat, I may very well move over from Parallels on my MBP but that's as far as I'd take it for now.