A good WC loop for the CPU will be a 120x3 rad, pump/res, CPU block, and hoses etc. About $300 or so.
If you want to WC the 3 GPU's your looking at close to $80 per card on the cheap end, might have to go a full cover block due to space and thats umm $120+ each card. Same 120x3 rad, same pump etc. in a whole second loop.
So, pretty easy to say your gonne be close to $900 total.
You don't need to cool anything else besides what I listed above. You can, but the $$ issue really clibms fast and has very very little benefit.
Two loops. Danger Den is okay, he does make some nice blocks, I use his GPU blocks myself. Thats all DD makes. All the rest is reselling. There are MANY MANY other and somewhat better parts out there.
Here is a quick links , please spend a LOT of hours of reading and learning. It's NOT like going to Best Buy to pick up a new DVD player.
Guides
http://forums.extremeoverclocking.com/showthread.php?t=282232 Pretty up to date info and buying guide
http://gilgameshreviews.com/index.php?option=com_content&view=article&id=75:hokiealumnus&catid=40verclocking-and-cooling&Itemid=86 Another good guide
http://forums.extremeoverclocking.com/showthread.php?t=312743 What to do once all the stuff is in the door
http://www.xtremesystems.org/forums/showthread.php?t=223835 Many build logs on MANY cases, great learning tool.
My latest rig:
http://www.ocforums.com/showthread.php?t=604016
Forums
http://www.xtremesystems.org/forums/index.php? Not a noob site, but great stickies
http://www.ocforums.com/ My fav, good peeps, know their stuff, less hardcore
http://www.over-clock.com/ivb/inde [...] opic=20277 A GREAT Europe site
http://www.overclock.net/water-cooling/ Decent site
Tests on equipment, not reviews, truly scientific tests
http://translate.google.com/transl [...] n&ie=UTF-8 Info on rad testing
http://www.xtremesystems.org/forums/showthread.php?t=220593 More rad testing
http://skinneelabs.com/ Host for Martins lab and some newer tests
http://www.skinneelabs.com/MartinsLiquidLab/ Test results, very technical
Stores
http://www.dangerden.com
http://www.petrastechshop.com/
http://www.sidewindercomputers.com/
http://www.jab-tech.com/
http://www.performance-pcs.com