Go for the 939 AMD X2 4200+ (2.2Ghz Dual Core) and a Asus A8N-SLI Deluxe/Premiumhttp://www.overclockers.co.uk/acatalog/Athlon_64X2_Bundles.html
Just remove the RAM from the bundle in you basket and you're sorted
That mobo works solidly and comes with gd utilities (AI Booster allows for easy overclocking, got my 4200 to run at 2.6Ghz with no voltage change and on the basic cpu fan).
Your RAM and Gcard should work fine with it too. Wise choice on waitin for DX10, and with AM2 its stil quite buggy. An there's no point as you'll have to wait and see just which motherboards (if any) will be compatable with DX10 cards.