I just tried XGL/Compiz using this http://www.compiz.net/viewtopic.php?id=389 howto and I have to say, I am completely flattened!
This stuff is so incredibly cool, I seriously doubt that Vista will be able to rival this, especially given the lead time till January 07.
And although everybody always warns about this being alpha stuff, I've been typing, surfing, mailing, using the window sorting functions, transparency (even on videos, it's CRAZY!) and spinning the cube like a madman and it hasn't shown a single glitch. CPU usage is bearable, doesn't cause my processor to scale up (except when I do 2 full rounds on the cube).
Do they still have a chance?