I assembled a computer from spare parts as an experimental watercooling system. The watercooling system consists of a 120vac water pump, a water block and reservoir off Ebay, tubing from Home Depot, fittings from Friedman Bros., and an old water chiller (garage sale find). The chiller has a refrigeration system in it(basically vapor phase cooling like what the Vapochill cases use).
Specs on the computer:
Gainward GeForce Ti 4200 w/80mm fan jimmied to the heatsink
2xKingston 512mb DDR333, 1gig total
Athlon XP 2400+
Boot drive: Seagate X15-36LP 18gb
Seagate Cheetah 18LP 9.1gb
Maxtor D740X 80gb FDB
IBM/Hitachi 120GXP 80gb
Onboard AC97 sound
Lite-On Combo CD-RW/DVD-ROM drive
Enermax 350w power supply.
The processor runs at ~22C/71F under load!
I haven't had any leaks yet, and only a minor condensation problem at one point.
I'll have to post some pics of this setup soon!