John:
I'm interested in Windows 7 and other coming attractions such as USB 3.0.

I'm under the impression that one is supposed to be able to run Windows XP apps in Windows Vista via one of its functions telling it to run them as such. I've had indifferent success with doing this, personally.

There are some things that Vista does better than XP, better than Linux, and for all I know, better than a MAC.