Well I ordered some bits and bobs and built my PC (well all except the RAM)
Q9450 Quadcore 2.6GHz 12MB L2 1333MHz FSB
2GB DDR2 1066 Corsair (2x1GB)
500GB HDD
MSI P35 Diamond
Vista ultimate 64 OEM with Nero8 suite (£104!)
560W PSU
Unfortunately the m/b only takes DDR3 memory, which I've now ordered and Scan are going to refund me the DDR2 cost when I return it, which is nice.
So come Tuesday I should have it up and running