I've used VPC technology for quite a while, but lately, I have been using it even more so. As I prepare the demos for my upcoming sessions, I find m yself loving and hating VPC at the same time. I love it because it is an isolated environment where you KNOW what is running in there. I hate it, because of the performance problems any virtualized environment encounters and the occasional corrupted file plus the large amount of disk space used.
VPC sp1 now has a "precompactor" tool that allows the compaction of a ".vhd" to really work. This improves the overall experience although it is a hassle at times.
One of the first VPC images I created still works. It is a Windows 98 SE VPC. I use it sparingly, but it is kinda cool to be able to pull that up. I still have a 8-year old PC with Win98SE on it. The VPC does run faster than the old PC, but it can't see USB ports and a few other things. I hear that many people like VMWare. I have seen it in action and used an image on a lab PC once. I have not created an image with VMWare, so my comparisons between the two products cannot be complete.