Another 2CPU'er welcome!
Here's a link to my K8WE dual opteron / SLI watercooling project;
http://forums.procooling.com/vbb/showthread.php?t=11010
I haven't updated / added to it recently; as far as water cooling parts go I pretty much have everything, still working with Trodas so that I can get my hands a double res based on his tank-o-matic design.
I'd definitely recommend a dual loop system. I don't think its possible to water cool the chipsets, because of their location near the PCI-E slots.