I must say that I am quite impressed. I just installed Vista Business edition on Virtual PC 2007 and considering it is running in a VM it is quite snappy. My host machine is a Dell Precision 370 P4 2.8Ghz with 2G RAM and I allocated around 800MB to the VM. When I try to get the performance index it fails with some complaint about invalid drivers but other than that everything seems to be running just fine.
Now I'm really tempted to put it on some real hardware...