Microsoft is giving away Virtual PC http://www.microsoft.com/windows/virtualpc/downloads/sp1.mspx I find it useful for testing D/L software to check it's operation or utility without having it attach it's tentacles to my real machines registry. Of course if you are installing XP (or any other operating system) you need the installation CD or floppies.
I never used a Virtual PC program until my boss got a MAC and is using a vitual program called Parallels desktop and it looks very neat. I read some great things about VMware workstation but a bit pricey $200.00 I last checked. I will check into it though.
I prefer VMWare too. If I remember correctly, when I tried Virtual PC it only supported Microsoft OSes and maybe OS/2, but not Linux or BSD. It depends on what you are doing, I found VMWare better for other OSes, but Virtual PC was better for things like DOS. I wanted to try a couple programs that I couldn't get running in DOSBox and tried real DOS on both. VMWare emulated some lesser used sound card, Sound Blaster PCI instead of SB 16 or even the older Sound Blaster Pro, and it was hard to find drivers for it compared to other sound cards.
This is just an update about VMware.... I didn't relize that this peace of software can eat up so much RAM, I have 2gb of ram and im down to 40mb at times...WWHHOOOAAAA I also relize im running 2 OS's but krwykeee. I can just image runniing this on my notebook. Probably slow as hell. Does anybody have suggestions or tips of anysort?