I guess at the time Kojn has a new box, he'd like to play other games as well. Not talking about the fact that a 3Ghz P4 isn't available anymore.
Intel has a nice and affordable CPU called Pentium Dual Core E6300 (no, not the Core2Duo E6300!!) at the moment. It's running at 2.8GHz default, and you can easily OC it to at least 3.6GHz if you really need it. From GBP 56 up. Moster bang for buck than phenoms, definately
It's hard to give you any recommendations concerning a mainboard. Take my advice, don't by Asrock mainboards. They're all big pieces of shit.
DDR2 RAM is getting more and more expensive atm. You will need 2 1GiB modules, 800MHz. Better: 2 2GiB modules 800MHz. Not so good: 4 modules.
GFX, well, go look for a Geforce 9600GT maybe from GBP 60 up, or if that's too expensive for you, get a 9600GSO, GBP 37 up.
Harddisk: Not that important. Don't buy PATA (old), buy a SATA (current). Maybe a Western Digital Caviar Blue 160GB (GBP 25,82 up), if that's big enough for you.
Case: try to get a used one.
PSU: cheap ones are not very recommendable in general. You will have to spend more than 20 bucks. The Corsair CX 400W is fair quality at a reasonable price and absolutely strong enough.
DVD Drive: who needs a DVD drive??
