You should really research around and check the stickies, but /spielON.
Base your system aroudn the cooling element. Radiator or heatercore, basically some auto AC Heatercore or a BIM,BIX,BIX2, Swifty 676, etc.
From there you get an idea of your needs.
Ultimate best performance: Storm G4, Maze4GPU, Tygon 1/2" tubing, 2-302 HC or similar dual pass variant, Iwaki mega-pump.
Realistic best performance: Dtek WW, MCP650/D4, Maze4GPU, 2-302 HC or similar dual pass variant, 1/2" Tygon.
Low flow rig of righteous temps: Swiftech 6002, 2-302 or similar dual pass variant, Hydor L30/Mag 3/Via Aqua/ or better pumps if you prefer.
10% antifreeze/ 90% distilled water, perhaps a drop or two of dye
two or four 120mm fans on the HC/rad as you prefer
reservoir or t line, as you prefer, go with t line (bias)
HC knowledge
Basics
Swiftech
DD
D-Tek
CrazyPC
CoolTechnica
Sidewinder
FrozenCPU
The Ubiquitous block comparison chart.
Procooling
Go to it.