I have a pretty good pc, or at least i think i do. It cost me £620 and was fitted by a dude at a computer fair. Now im thinking how much i could save if i made one myself. I'd be buying everything from the computer fair since savings are at the very least 25%. Any tips on what are the best components i can buy?

Wrong forum, sir, but anyways...

But for £600, you could build a fairly decent system, especially if you choose a mid-class XP over a mid-class p4 (will give you ample room to go better on the video card).

If you don't mind purchasing generic things such as a generic case, generic keyboard/mouse/speakers, et cetera, you can easily give yourself another $75-150 to indulge on the much more important aspects, CPU/Ram/Motherboard.