Benchmarks available here comparing Virtual PC 2004 to VMWare performance.
The author's conclusion:
From the benchmark results i've obtained, it's perfectly valid to say that VMWare 4.0 performs better in general than Virtual PC 2004. Take in mind that this is under Windows 98SE. I don't know how VMWare and VPC perform with Linux or other guest OSes. I've FreeBSD 4.9 installed on my VPC2004-Trial and it runs very well, altough the X GUI is somewhat slow.
The advantage of Virtual PC 2004 (and the reason that makes me like it so much) is the standard hardware emulated: S3 Trio, SoundBlaster 16 and a standard DEC network card. In the case of VMWare, the guest operating system needs a special video driver (SVGA II) to display more than an obsolete 640x480, 16 color display. If you want to run, e.g FreeBSD, you are with no luck.
I agree. This is one of the biggest reasons I'm using Virtual PC 2004 now. I've found the performance to be negligible (as his benchmarks certainly attest to).
It also makes me very happy to hear that Virtual Server is entering a public beta. I filled out the survey and now I wait with baited breath. I've seen this product in the past (I think it was an alpha release; and it expired a long time ago). But this is a much better solution if, as the name implies, you want to run a 'server' as opposed to a client machine. Basically, it's the same thing as Virtual PC except it runs as a service and doesn't require you to manually start it and keep it running. It also has some really neat features, like CPU throttling (in other words, you can set it so it will be using 100% CPU as far as it's concerned, but only some percentage of your total CPU).
Sigh. I guess it's time to bump up my RAM. I have to check what my config is now and whether I have a free slot.
Yes, Bill, 640k should be plenty.