I am using VM for a while now, most of the time to have alpha, ctp, beta...
My issue was that my main VM was starting to be really big: 8.5Gb and I had to do something to save some disk space.
If you are like me and you are using Groove. I recommend you to read Marc Olson's Groove "12" Blog. Tomorrow Marc will blog about the integration of InfoPath and Groove 12, such an integration is so promising.
VMWare realized a Player version of there virtualization software: VMWare Player. Basically it is a version of VMWare that let you do almost everything except creating new Virtual Machine. The good point is that it comes for free. And even better you can download optimized, preconfigured virtual machines coming with applications from IBM Software, Oracle, BEA, MySQL, Red Hat, Novell, and others, from the VMware VMTN Virtual Machine Center. You might download the player on this page.
I am curious to see Microsoft reaction with Virtual PC.