You can also get things from newegg.CA or memoryexpress.com. Memory Express is an Alberta based company, but you shouldn't have any trouble getting it to Quebec.
As for you saying that HDD doesn't matter - you're mistaken there...badly. Its one of those things that people tend to disregard, but then regret it immensly later. Go with a WD Caviar Black or a Spinpoint. Those are easily the best HDD's out there. The Black even beats the Velociraptor in some tests. It'll help you boot up faster and load programs quite a bit faster. Whatever you do, don't skimp on the HDD. I'd even consider a SSD in addition to a spacious HDD.
For the cooler, you could look into a Corsair H70 or a high end air cooler (Noctua NH-D14, Thermalright Archon, Thermalright Silver Arrow, etc). High end air cooler run about $80 CAD, whereas the H70 goes for about $100. You could also stick with the stock cooler for now then get the H100 for about $120 (but good luck finding them, its all sold out).
As for GPU, the 6950 is faster than the GTX 560 - not by a whole lot, but still faster. This is coming from a Nvidia fanboi - but for the money, the 6950 is better. You also look into a GTX 570 which runs about $320 CAD (before rebates).
You could also reconsider that case - unless you have space restrictions. Go with a HAF 922 at least or even a Cooler Master 690 II Adv. They offer more space to work with and more air flow.
So, price wise, a fast HDD would cost about $70 (or 20 more than your suggestion), Cooler less than $100, GTX 570 about $300, and the case would be about $100 (depending on where you buy/ model, also only $50 more than your suggestion.
So, total would be about $450 - $500 more, which is I think quite well in your budget.
Links to items:
WD Caviar Black:
GTX 570: (slightly more expensive, but well worth the extra)
HAF 922 / 690 II Adv - too much price variation to list here.