I wanted to get working on Katmai a little, but not being brave and seeing the release notes that it can't run side by side with SQL Server 2000 (who decided that?), I wanted to put it in a VM.
So I fired up Virtual PC, created a new VM, and...
Nothing. It started the boot and froze. I'd selected Windows 2003 as the base image and for some weird reason thought I'd get a W2K3 install. It was then that I realized I don't have a blank Windows 2003 image. So I'm installing W2K3 now on a VM and when I'm done, I'll shut it down and copy the file off to another place to hold as a template.
I haven't done much VM work lately, but I used to keep spare images around as templates, which allowed me to quickly and easily test installs.
So a tip: Keep at least a Win XP and a Win 2K3 image handy. Or Vista if your hardware supports it.