Now that I'm running Vista with IE7 on my main work machine, I need to ensure that I have an easy way to test our web applications under IE6 on XP (which is the configuration used by most of our users). Fortunately, Virtual PC offers exactly the solution that I need (incidentally, Virtual PC 2004 won't work on Vista - you'll need to download a beta version of Virtual PC 2007 from Microsoft Connect).
So on Wednesday I spent very many hours building a clean Virtual PC image of XP Professional with Service Pack 2 and all the updates (except, obviously, for the IE7 update). Do you know how many updates there were to download and install? Sixty-Four! And that's only the updates since SP2. You can imagine how long they took to install on a VPC.
Guess what I read on Thursday? This entry on the IEBlog, describing exactly the situation that I faced, and announcing the availability of a free VPC disk image containing a pre-activated Windows XP SP2, IE6 and the IE7 Readiness Toolkit!