an alienware laptop for college? i know what you'll be doing secretly when no teacher's looking, just don't try to yell "HEADSHOT F*** YEH" too loud
for futureproofness, i'd say go with vista, but for presentproofness, I hear of many people getting fed up with vista and "upgrading" (in their own words) to xp to be able to play current gen games. I'm still on XP, and I play all the most recent games on highest spec etc just fine, so i have no reason to "downgrade" to vista
secondly, i dont think i would be able to cope with vista's nanny reputation, where you can't do anything without responding to 10 confirmations asking "are you sure you want to do this" or w/e, that I hear so much about.
and with the more bad stuff I hear about vista, as much as i really really REALLY HATE LINUX i think i'd be more than willing to switch to that than have to go to vista...
furthermore, it is possible to run DX10 on XP, and to set it up is very simple, and it also works. Company of Heros FPS increased by 10hz.