Originally posted by: Match
I don't know about pre-built systems, but if you want to assemble something yourself...
The best cpu block that I've heard of is the Cascade. It's designed by a guy in Australia and right now I think he's just working through a machine shop to get blocks out. You can check out
this thread for more info.
For a pump, I second the recommendation for an Eheim, and I've also heard that danner mags are very good. If you have money to burn, Iwaki is supposed to make the best, but I think their pumps are well over $100.
As far as a radiator goes, get a heatercore for a car. Get one that would allow 2x120mm fans if you have the room. Heatercores are pretty efficient and they have relatively low flow restriction. You can just go to your local autoparts store, or even a junk yard to pick one up. This will save you money over buying a "watercooling" radiator which I don't think would have any advantage in performance, but would cost you more.