I have an Antec CP-1000 1000W PSU its 2 years old.
MB - ASUS P6X58D Premium
CPU - i7 930
GPU - Radeon HD 5870
RAM - 3 x 2gb g.skill at 1600.
I'm in the US so maybe I'll check Staples out like you said.
Yeah, you will only need a good 500-600w PSU and they sell Antec there.