I was using this PSU calculator on the net and it told me I needed just shy of a 900 watt PSU. can anyone confirm this? It seems like a lot but ive been wrong before. The system I will be building is as follows:
cpu: AMD Phenom II X4 965 Black Edition Deneb 3.4GHz Socket AM3 125W Quad-Core Processor HDZ965FBGMBOX
What PSU calculator were you using? Looking at your parts, even if you add a second GTX 460 and OC quite a bit you can get by just fine with plenty of extra power with a good 750W unit like the Corsair 750TX, Antec TP-750, or XFX 750W.