get the normal retail or OEM q6600 and depending upon how far you want to overclock that q6600, get a better cooler
i would personally go with
Your basket
Product Name Qty Price Line Total
Intel Core 2 Quad Pro Q6600 "Energy Efficient SLACR 95W Edition" 2.40GHz (1066FSB) - OEM £129.99
(£149.49) £129.99
(£149.49)
Thermalright TRUE Black 120 CPU Cooler (Socket AM2/LGA775) £34.99
(£40.24) £34.99
(£40.24)
Sharkoon Silent Eagle 2000 120mm Fan - 3/4 Pin £7.99
(£9.19) £7.99
(£9.19)
Subtotal £172.97
£198.92 inc VAT (this is £4 more then your cpu and cooler selection)
for the cpu and cooler
the vx450 will be fine
also invest in 4GB of RAM (2x2GB)
if you stick with the ac7 pro cooler, it comes with mx-2 pre -applied and is quite good, so you dont need to buy AS5 unless you want to. preformance wise the two paste are almost equal.