I have both, my macbook for EVERYTHING, and a gateway (BOOOO) notebook for halo, matlab, and PSPICE, along with other EE programs.
First response to Vista is that it looks much better than XP, XP makes me want to vomit.
After about 5 minutes of using it though, Vista makes me nauseas with all the visuals. Aero is crap in my opinion, I cant make it how I like it. In terms of usability, its Windows. Also it makes my notebook run super hot.
Let me put it this way, if CrossOver worked for ALL windows programs, I would BURN my copies of XP and VISTA.
OS X and Linux are all the OSes that Id ever need, if I could run those programs on it.