The XSPC 750 is a wonderful "all in one" cooler to start with. You can add to it later if you wish, but with your hardware, you won't need to. One thing I would suggest with that kit ... by some after market tubing. Yeah it comes with 2m of tubing already, but it's cheap stuff that tends to "cloud up" after a time. I'd personally get some Durelene tubing from here in addition: http://www.sidewindercomputers.com/dupvctu7id5o.html
You also might want to pick up a "silver coil" to prevent "biologicals" forming in your distilled water: http://www.frozencpu.com/products/11441/ex-tub-705/IandH_Silver_KillCoils_-_Antimicrobial_999_Fine_Silver_Tubing_Reservoir_Strip.html
I personally water cool my CPU and both GPU's on the same loop. Granted it's a much bigger loop, but still, same principles.
With that system, you can start out with just water cooling the CPU, and later, add your video card.
Even if you don't overclock your video card, adding water cooling to it will allow your system to run very quiet, especially when you are pushing that video card from gaming or folding.
I would, for the first time water cooler, just go with a single loop. The temperature difference between a single and a dual loop is only 1C or 2C, and unless you are really going to push the envelope, the added complexity of a dual loop isn't worth it, IMO.