This is quite similar to my approach: http://blog.dotsmart.net/2009/06/24/using-windows-7s-xp-mode-to-run-ie-6-and-ie-7-side-by-side/. I set up the VMs slightly differently (I didn't use the "Differencing" disk option) but the end result is the same.

They end up looking like this on the Start Menu: http://i.imgur.com/yUYTX39.png

And run on the desktop without having to have a full-screen VM window.