Pete LePage posts that there is a new Virtual PC image preloaded with Windows XP SP2, IE6 and the IE7 Readiness Kit:

Now you can install IE7 on your main machine for development, and get all the advantages of IE7, like the RSS platform, native XMLHTTP stack, and improved security, while still running IE6 simultaneously in the VPC on the same computer. Most importantly, you don’t even have to buy an additional Windows license. The VPC image runs in a virtual machine that offers all of the functionality of a full IE6 installation without giving it any access to its host machine’s hard drive, registry, etc. You can make as many modifications as you want to the virtual machine without affecting your host installation at all. 

See Pete's post for details, or download the VPC image here.

-Chris