It's cooling the cpu the vga and 2 hd. Cpu (P4 2Ghz) @ idle is 32 C. I made it out of copper tubing and couplings from the diy shop. No soldering involved, hardest work was sawing the tubes. Only fan left is a temp controlled papst in the psu running at approx 1000 rpm. Follow this link to see some pics.
http://www.xs4all.nl/~philippo/Watercool/