I'm just starting out with w/cooling myself. About to start my new build (see post:
http://forums.procooling.com/vbb/sho...510#post172510).
I recommend that you use a dual loop setup. One loop for your CPU (and possibly including your NB/Mosfets etc. if you are hardcore...), and a separate loop for you GPU(s).
GPUs are happy running hot (and therefore OK with, and create, high water temps), whereas CPUs are a little more sensitive to temp and run cooler. If you want to OC the hell out of both parts, then for goodness sake don't dump the heat from your OCed GPU(s) into the water that is trying to cool the delicate CPU... You'll severely restrict how far you can push the CPU.
Good luck with the build and post a build log!
4rkon