There are two major things regarding your new computer I want you to know. First, eventually it will run Windows Vista. Even if you buy it now with Windows XP on it, at some point next this year you will want to switch to Vista. Second thing is that Windows Vista is very demanding on memory and video card. Not a processor type or speed but amount of memory in both motherboard and video card and video card itself.
So, if you see a very attractive PC shopping deal, check, first of all, those two thing. The general rule is, of course, the more the better. But the least is 1GB of motherboard memory and 256MB of video card memory. There are lots of powerful PC system out there for sale with huge hard drives, memory slots, latest and greatest CPUs, but that is not what you need firstly. I'm not trying to say that storage or CPU frequency are not important. They are less important for Windows Vista. Or if you got them first, but your PC memory is 512MB only, and configuration has integrated video solution sharing memory with motherboard, you're not gonna enjoy Windows Vista.