I think that if I had a unlimited budget for this build I could really have some fun here.
Reality tells me that my build is not going to be the system my heart tells me I want to build. It is going to be what my pocketbook lets me build.
Even a used rampage III board on Ebay is not cheap. It would be dangerous to buy one on Ebay because of possible problems like bent pins. I have seen them listed with descriptions like "you can bend the pins back" or "one pin missing, but it still works fine". Not going to work for me so a cheaper build is in order.
Any input on the ASUS P6X58D-E MB? Seems OK from the write-ups and more in my price range at the moment.

Case HAF-932 is excellent too. I have two rigs with Cooler Master boxes (Cosmos) and I am very happy with them.

Thermaltake Toughpower are also excellent. I have at least ten units in my rigs. As a new rig you should go for 80Plus Gold standard if possible.

Regarding GPU I am an unconditional Nvidia GeForce addict so no comment.

Hypernova, I am glad I got the power supply with the 80 plus standard now that you pointed it out and I researched it a bit. (by the way, I did put a GTX470 in the wifes computor for her and it is running great) I bought the 2 5850's pretty cheap so thats why I am starting with them. I liked your idea of the 590's and did not want to put too much money into the GPU's because of the future upgrade.

nanoprobe, I was thinking LGA1366 because of the upgradability to the 6 core processors later on. Will the Sandy Bridge 1156 have the upgrade options that the 1366 has later on?

I am still looking at the ASUS P6X58D-E board since it seems to have good write-ups and the cost is not to bad. The price on the i7-950 would be in my budget at the moment. The 990X recomended by Hypernova would break the bank at the moment.(but it sure looks good, "as I wipe the drool from my chin" )

I am now up to my neck in this water cooling issue. I am thinking of a swiftech triple 120mm radiator up top. I would put the reservoir up top in the top 2 5.5" bays so that the fill hole was accessable to the existing case fill hole. Any thoughts on doing the GPU's also, or should I let the case fans take care of their heat? I am not sure if it would make sense, or even work to put the 2 GPU's in the same loop as the CPU on the triple radiator. Radiator/resevoir/pump/CPU/GPU/GPU. The rear fan on the case could be replaced with a single radiator but I don't know if that would be enough to cool the 2 5850's. (the single would be in addition to the triple and dedicated to the 2-GPU's)

The new generation of CPU's for Sandy Bridge are clearly a newer generation. The same technology in a six core format will beat the 980X straight out with much less energy consumption clock per clock, and higher overclockability with less heat temps etc.. No doubt. And it is already known that an 8 core will be coming in 2012. So the 1366 socket will be the high end solution until 2012 then it is finished, there will be no new CPU's for that architecture. This seems logical, as an 8 core based on the 980X design would have a too high TDP and would be much too expensive. The Sandy Bridge Quads show that an 8 Core SB CPU is feasible at a similar or lower price of the 980X today with much better performance.
The main problem is about the motherboard compatibility. When these new 6 and 8 core CPU's will appear in 2012 will the present SB motherboards be still compatible or will a new socket/chipset needed for those top performers. For me this is the major issue. If you buy an SB solution today and you do not plan a CPU upgrade then fine SB is the answer. But if the present solution is just as a transition for the coming top CPU's mainly 8 core then it is not clear. What seems to be clear is that the 1366 is a dead end for a new build today. On the other hand a 980X is still a top performer for crunching and unbeatable on runtime scores and will stay so until 2012. The problem with Intel is that they do not hesitate to introduce new chipsets as often as they introduce CPU's. It is really a very negative marketing approach. It is as if they had a kind of partnership with motherboard manufacturers to push for motherboard renewal as often as possible.
The issue of the motherboard compatibility is not a big one if your machine is designed just to crunch full time and nothing else. Then changing CPU and motherboard and reinstall the OS, Boinc is not really an issue, done in max 1 and 1/2 hour. But if the machine is your personal desktop, then changing motherboard and CPU becomes a big issue and you do not want to do it too often. In my personal case when I change my personal desktop with a new one it takes me a full week-end to do. I do this once in two years if not obliged.

Dan, as socket 1155 is replacing 1156 socket 1356 will be replacing 1366. IMHO the newer sockets is the way to go. it may be worth your while to wait and see how SB plays out. I believe there will 6 and even 8 core versions before the end of 2011. The setback the Intel has had with the 1155 chipset may push the release of new 6 and 8s back some but with the 22nm Ivey Bridge chips on the horizon I would not invest in socket 1366 at this time. The only caveat to that would be if the forthcoming socket 2011 chips will work on a 1366 socket motherboard. I have read conflicting reports on that. Are we confused yet?