Hi, this is the first time i have done a full spec for anyone, but seeing as no one else has thus far here goes... I'm assuming the case you have is ATX, is that right?
Apologies if i have got any of this wrong, hopefully someone else will look through (no doubt) and amend. I would suggest getting a new power supply though... search these forums for q-tec psu's and you will find a trail of woe. The last thing you want is for it to go KABOOM! and they do, which is fine, but not when they take the rest of your equipment with it!
CP-117-AM AMD Athlon 64 3000+ Venice 90nm (Socket 939) - Retail (ADA3000BPBOX) (CP-117-AM)
£65.95 £65.95
MB-002-AK Asrock 939Dual-SATA2 (Socket 939 & Upgradable to AM2) AGP & PCI-Express Motherboard (MB-002-AK)
£36.95 £36.95
MY-004-OK OcUK Value 1GB (2x512MB) PC3200 184pin DDR Memory Dual Channel Kit (MY-004-OK)
£47.95 £47.95
CD-019-SO Sony CRX320EE CDRW/DVD Combi Drive (Beige) - OEM (CD-019-SO)
£15.95 £15.95
HD-051-SE Seagate Barracuda 7200.9 80GB ST3808110AS SATA-II 8MB Cache - OEM (HD-051-SE)
£29.95 £29.95
GX-037-GW Gainward BLISS GeForce 7300 GS 256MB DDR2 TV-Out/DVI (PCI-Express) - Retail (471846200-7661) (GX-037-GW)
£41.95 £41.95
Subtotal £238.70
Shipping (City Link Parcel Next Day (Delivered Mon-Fri)) £8.95
VAT £43.34
Total £290.99
So about fourty quid over your budget... cant seem to get much cheaper than that, and that graphics isnt great either, but give headroom for upgrading and also missing the PSU.. which i really do think you'd be better off getting.
If you do decide to get a new PSU then ask the guys here, unfortunately i dont know much in the way of reliable to price ratio Power supplies.
Dunno if that helps or hinders... but there it is!