DangerDen and Overclock-Watercool make some very efficient waterblocks. The only 2 pumps I've played with have been Supreme Mag drives from Petsmart. They're cheap, and often quiet, but not always quiet. I've heard Eheim is alot better, I believe you can get Eheim's here:
http://www.petwhse.com/webstore/webs...E?OpenDocument
Alot of watercooling people use them and love 'em, they're just a bit more expensive tho. For a radiator, yes, a transmission cooler will work, but the radiator technology is progressing rapidly and tranny oil coolers aren't easily fit into a case. OverClock-Watercool has 3 different small radiators, and DangerDen has a huge cube radiator that'll fit great if you have a full tower case. Hope that info helps.
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The UnaClocker
Overclock till it goes BOOM!
Watercooler extraordinaire!