Id prefer to do both. Get full watercooling, as normal, then useing a cheap freezer, chill the water, effectivly cooling gpu, nb and cpu. the watertemp can much easyer be controled to prevent the need for condensation proofing, but if not, you could probably manage close to or below sub zero temps with it.
kez - price is the reson Im diy'ing my blocks. pic of my northbridge #rotor style block made with nothing more than a hand drill and a dremmel. Only problem with diy'ing is the barbs - most people do not have a drill capable of holes big enough for the barbs unless they used 10mm OD ones, though some might do 13mm. Ive had to get my dad to drill the 12.7mm holes in the lid as i dislike barbs, and would prefer soldered copper piping, as its more reliable. My gpu block is whitewater style one, and is also just waiting for the top to be drilled. My cpu one may become a cascade style one, but they are hard to design, I will have to think about it some more (meaning i cant w/c my cpu for a while, and have to keep using the slk800..)
Also read this about the rbx/tdx - http://www.procooling.com/reviews/ht...block_revi.php