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A good place to start would be AquaStealth. They make some very good water cooling kits. If you want more info talk to our resident water cooling expert, WarCon. He knows his sh!t when it comes to water cooling. >>
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Hardly an expert......
For a kit price, I would recommend the Aquastealth II with AquaCoil upgrade(20 passes of copper with tons of fin's and a 120mm H1A Panaflo). Get the lexan holddown too, Don't use your lugs for they are simply not meant for a big metal block with pipes hanging off of it. This kit will handle a peltier when and if you even want to add it or voltage mods.
The leufken kit is decent, but not really for high performance cooling. It's radiator doesn't provide enough surface area for water contact or air contact. So it simply will not cool as well as the block style radiator's like the aquacoil. There are a few of the block style coolers out there though and I imagine they all perform well, but all cost a pretty penny and are hard to get in cases. I managed to get one in my 7237 with some serious mods to the 3.5" drive holder and the front metal. I also drilled extra holes and enlarged them all in my front bezel to allow good air flow.
If you want recommends on isolated parts, I would consider the DangerDen waterblock the Maze 2. Any of the block style radiators are going to perform well. And I would get a good pump that will last, because if it fails your chip will die. I have heard good things about Eheim pumps and Eugene Danner Mag Drive pumps. If you run your cooler in sealed mode then you won't need a reservior, but you will need fill valve's.
I also recommend water wetter (can be found in most large auto parts stores) for $8 at 50-1 ratio. One bottle will last you a very long time. This is the tested and tried ratio that gives the best performance.
I think thats enough to chew on for a bit.......