Making a computer now would be like getting a new Playstation or PS2 when you know that PS3 is just around the corner.
Couldn't you wait until the Vista Operating System, the *better* Core Duo-compatible motherboards, and the DirectX10 Video Cards are out (around the beginning of next year)? That's what I'm doing--I want to be able to have a future-proof setup, which will only require an occasional upgrade every so often without worrying that components will go stale. I will hopefully keep upgrading it for a few years until something new comes out that requires I make a new computer (in which case I will give the old one to my brother or sell it).
If you need something to do school work with, go REALLY cheap or stick with what you already have unless you don't really care about being prepared for an upgrade path. Plan ahead and leave some space for the newest components (for example, the DirectX10 video cards will require more PSU wattage and so you might want to get a case that can hold large PSUs).
However my knowledge of computers are limited, I've never built a system before. I'm just going by what I learned on the forums and everywhere else. Anyone who knows better, please correct me if I'm wrong on any point.