[llamabeast]

With regard to graphics cards, I believe the amount of memory is not the best descriptor of quality, and sometimes crappy cards are presented as "512MB!!" when the card is actually slow and having a big memory is unimportant. That said I don't know how to more sensibly differentiate card speed; I've only looked into it for desktops, and presumably the situation is confusingly different for laptops.

Definitely Windows 7 above Vista. Vista is horrible, and Windows 7 is considered a big improvement (and faster!). Then once you have your computer, personally I would recommend trying out Ubuntu (which is a free alternative to Windows, and you can have both on your computer at the same time; lots of people here use Ubuntu or other Linux variants).