Ran across this movie this morning while reading the Mac boards. It shows Windows running in a window on the Mac while installing stuff and just using Windows XP.
http://www.prodedgy.com/article/52
It really shows off just how fast this is.
I was using my neighbor's Mactell machine last night to test a bunch of my web pages in Windows and was blown away at how fast it runs even while doing stuff on the Mac at the same time. It was sweet being able to test stuff in Safari, Firefox, and Windows IE all at the same time as well as testing movies in Windows media player and QuickTime all at the same time.