Well, yea, I do know a bit about building computers.
Firstly, you'll need a motherboard, be sure to note down the CPU-socket type, RAM type and if it uses PCI-Express (which most new motherboards/computers does).
Then when you've found a motherboard suiting your needs you need to find a CPU with the same socket as you have on your motherboard (or else it won't fit).
As for RAM, as long as it fits with the specifications on the motherboard, you can pretty much pick whatever you want, but I would recommend at minimum 2GB.
I suspect you're going to need a graphics card too.
So the only thing you need to watch is if it's PCI-Express or use the old technology AGP, cause if it uses the old one, it won't fit with your motherboard. (If you haven't specifically asked/looked for AGP support on it)
You'll also need a harddisc if you haven't got one already and a proper sound card.
And then the boring thing: software, Windows is always easy to use. But cost a lot if you're going to buy it....
And yea, another important thing, you'll need a chassis and power supply and most likely a cooling system and of course peripherals or however it's spelled, you know: mouse, keyboard, screen, printer.
You could also go read:
http://www.tomshardware.com/2007/09/18/ .... st_system/
or
http://www.tomshardware.com/2007/09/19/ .... nd_system/
PS. There's probably something I've left out, so feel free to correct me.
