Use shopbot.ca to find the lowest prices on all those components and you can PM them @ NCIX.
1) Get the AMD Phenom II X4 955 BE its cheaper by $20 and you can jsut OC it to the 970 by changing the multiplier.
2) Antec twelve hundred is nice, but the cable maangement isnt very good. Consider the Coolermaster HAF X, should be in the same price range.
3) For video cards/Motherboards, if you want to go single gpu the mobo you have now is fine. If you want to go multi gpu, I would consider an 890gx mobo such as the gigabyte 890gpa-ud3h which is a bit more expensive but allows crossfire at 8x/8x on the two pci-express slots. You can also get two Radeon 6870 cards, which scale really well.
4) You're current power supply is kind of high. You could probably get away with a 750W PSU. Also it is more expensive but consider a modular power supply. It helps make you're build much neater.