Listen to Parker.

Personally, if I were going back to college, I'd build a desktop that could do all my video and gaming ($500-800), buy a small portable laptop to take to class ($700-1200), and network the two together. The smaller laptops tend to have better battery life because they don't have all the bells and whistles that need power and have smaller screens. Also, with a desktop/laptop combo, you get TONS of storage. That means you can keep back up copies available in case one system goes down. If you download a lot, you can keep the desktop on dowloading files while you go to class with the laptop.

If you go with Vista, you'll have to get a bigger, beefier machine. It is a memory, processor AND video hog. XP you can run on anything made these days.