ouch1 :
Don't forget Danger Den. They are one of the best producers of liquid cooling equipment out there:
http://www.dangerden.com
-ouch1
I wouldnt say that they are one of the best producers. They really have only produced a line of average performing blocks, and some other problematic products. They do sell alot of good things on their site, and they are the only importer of Thermochill rads (I think at least).
The Swiftech kit mentioned earlier is a good option. DD's kits do seem a little expensive to me, but a really good custom loop is not going to come cheap. I would completely steer clear of XSPC kits. Another option is a kit from Petras Tech Shop mentioned earlier. Maybe a PTS kit for the first one, and a Swiftech kit for the second one. Of course another option is building a custom loop, which can be done pretty easily. I'll even go ahead and list the best for price and performance for each component.
CPU Block
Performance: D-Tek Fuzion and EK Supreme (Both are pretty equal in price/performance), also a Swiftech GTX w/ Copper housing is another option, with similar performance, but a higher price.
Price: Apogee GT
Accessory Blocks
Performance: Although there arent many blocks for this category, I believe the Swiftech MCW30 is the cheapest and best performing NB block. For best aesthetics, a set of 2 mosfet, NB, and SB blocks from EK are hard to beat.
Price: None
GPU Blocks
Performance: The best performing blocks, are GPU only w/ RAMsinks, however, most people believe that Full Cover blocks are much more appealing. For 8800 Cards, the Swiftech Stealth provides the performance of a GPU only block with the aesthetics of a Full Cover. For other cards, most would agree that EK makes the best looking blocks. The best Die-only blocks are the MCW-60 from Swiftech and the Fuzion GPU from D-Tek, both have similar performance, but the Fuzion has a rather large pressure drop, which is why most go with the MCW-60.
Price: The good old Maze 5's are only a few bucks cheaper than the other GPU only blocks mentioned
Radiators
Performance: Thermochill
Price: Swiftech (I really dont see why people buy other radiators than these 2)
Pumps
Performance: Many would say that the Japanese Iwakis are the best pumps, 30 ft. of head press. on the RD-30 is pretty amazing, be warned that an additional power supply and some wiring skills are required to get the most out of these pumps.
Price: The Laing D5 and DDC are the best options price wise. The DDC (sold under a few other names like the Swiftech MCP350/355) provides good head pressure, with very little heat dump, and you can buy different tops (such as Petras top) to change the tubing diameter from 3/8" to 1/2" as well as some pump properties. However, most people are switching to the D5 these days, simply because there have been alot of DDC failures (D5 also sold under other names such as Swiftech MCP655). The D5 has less head pressure, but better overall flow.
Reservoirs
Performance: There is really no performance gain to having a Res. so as long as its not that one DD bay res, or made of Aluminum, its really your choice.
Price: T-Line
Tubing
Performance: Tygon is supposed to give you better bends with less chance of kinking.
Price: Masterkleer is a cheaper option. Also, it doesnt really make much of a difference between tubing sizes, only potentially 1 or 2 degrees difference between the smallest and largest tubing.
If you have any other questions feel free to ask.