Here is what I would recommend and it is all from newegg.ca so price is CAD. It is 836 CAD including shipping (I just picked a postal code in quebec for reference) but has a $10 USD and $15 CAD rebate. And you get to keep your 6 core processor with an aftermarket cooler that will help you with overclocking.
Whoops, forget optical drive. Total is 847 CAD before rebates. You could always save money by dropping to a EVGA GTX 460 1gb (~25 CAD) and with rebates that puts you 3 under 800 CAD)
Also was curious, do you need an Operating System? If you do, then I would recommend something closer to Batuchka's build and use savings to grab windows 7 home 64 bit