CPU:
Q6600
CPU Cooler: Thermalright Ultra 120 Extreme/Ultima 90 or
Scythe Ninja
Motherboard:
Abit IP-35 Dark Raider or Abit X38 Quad GT
Memory: 4GB DDR2 PC6400 (800MHz) 4-4-4-12 timings
Graphics Card: 8800 GTS 512MB or
3870 X2 (look for a good deal, seen them for £230
Hard Drive:
Western Digital AAKS, Whatever size you fancy
Case:
Antec P182, Antec 900, Silverstone TJ-05 to TJ-10 (not 08 as it is uATX), Coolermaster CM-690
PSU: Corsair HX620W, Enermax Liberty -
i'd get the 520w HX
DVD: Samsung
There you go that should be a decent starting point
Should be well within your budget.
Oh plus a copy of Windows if you don't already have a retail version to install on it.