Watercooling is more for the enthusiast crowd who really love their computers. (Or just people who just have a ton of money)
If you really just wanted something for the performance/price aspect, I suggest sticking with air and going with something like a Megahalem or Noctua heatsink.
As for the XSPC components, they are all good. The Raystorm is an EXCELLENT waterblock (I'm using one right now!) and the radiator is very adequate. If you plan on expanding from a XSPC kit, then I recommend upgrading the reservoir/pump combo since the pump they include is not powerful enough to really drive a GPU/CPU loop.
As for me, I love my watercooling loop and honestly would find it very hard to go back to air. Idling my 4.3GHZ 3770K at 20C is quite a feat. ;)