Rig Building Help

Well, I've only just joined the forum after being directed here by a friend. He highly recommended coming here for all my Rig-building needs.

Simply, I want to build a very good PC. Mostly it'll be for gaming, but I also want to learn more about the process, since I've always used a computer for gaming and other purposes, however I actually know very little about them. Most of the things people say confuse me and finding a "Computer guide 101" Isn't exactly easy.

If there is anymore information you need from me then I'm happy to share, however like I said, I know very little about the technicalities of PC's, only that I want to know more and I like playing games on them :).

Budget? Any current hardware?
Are you looking to jump straight into the deep end (all components from scratch)? Maybe worth considering a part built PC.
What sort of games do you play? (or plan to!)

Well the budget is difficult to say, I don't have any spending money at all at the moment, but if I get a job, then all the money from that can pretty much be spent on this project, so lets say for hypothetical sake, it could be up to about £1000, as don't have any outgoing expenses. That will/can of course be altered when the job situation develops.

My current setup is, well I'm not too sure to be honest, it's 'self built' in the respect that someone else built it for me and it is probably mid range in terms of power. The specs I know off hand is, 3327 MB of RAM and an AMD Athlon 64 X2 Dual Core Processor 5600+ 2.80 GHz Processor. None of that makes all that much sense to me, but as far as I know its mediocre.

I'd quite like this to be sort of a new hobby, so I'm happy to build it from scratch, I'm not sure a partially built PC would feel like mine or not, so perhaps a completely self built one is ideal?

At the moment I play Diablo II (High 5 to those who play it) and Counter Strike Source. I would probably buy more games with money and I'd be looking at games requiring a high end PC, so with money comes better games and hopefully a very good PC.