After looking at the site, the board you'll want that they have will probably be the ga-ep35-ds3. The "e" in front of the "p" designates their new generation of boards that are supposed to be more energy efficient. Also, it almost doesn't make sense not to get 4GB these days since it costs so little more to get 4GB over 2GB.
Straight from ebuyer
CPU: Q6600 £130
MOBO: ASUS P5KC £70
RAM: OCZ 2GB Kit £28
GPU: PowerColor HD 4850 £118
PSU: Corsair 550W VX £55
COOLER: CoolerMaster Hyper TX 2 £10
HDD: Seagate ST3250410AS 250GB £33
DVD: Pioneer DVR-212 18X SATA DVD £12
CASE: Xion Stacker Black Full Tower £40
PASTE: Arctic Silver 5 £4
"if you have a piggy jar to break for a few more £ do it to get a higher wattage PSU (SilverPower 850W for £75 or Corsair TX 750W for £84) because your motherboard can hold more and it would be a shame that you can not upgrade because your PSU doesn't have enough juice."
RAM +2gb (for 4gb RAM) £28
HDD +250 (for RAID0 possibly..?) £33
another 4850??? (need better PSU for that though)