www.newegg.com won't ship to Canada. I don't know if they ship to P.O. boxes in the US, or what customs fees you might have to pay if you do that.
GTX 295 is more powerful than the HD 4870 X2. Get a GTX 295 if you have a 30" monitor and play at 2560x1600. If you want to play Crysis wait until they fix the drivers.
At 1920x1200 or less the HD 4870 X2 is good enough IMO. It can serve 60 fps or more in almost any game, and the typical LCD can't refresh fast enough to display more than 60 fps anyway.
The PC P&C 750W is great. I have one myself. However it's too small for two GTX 295 or two HD 4870 X2, let alone 3. Also, scaling with 4 or 6 GPUs is horrible, for both nVidia and ATI. That means you can replace the P6T with some cheaper x58 that has only 2 video card slots, maybe even one with no SLI support, and you won't lose anything.