I'd go with 4gb of 1066mhz RAM, personally. If you're running Vista, see if you can fit in 8gb.
What they mean about SLI, btw, is that you'll have to choose between either using SLI on one monitor, and the other monitor not recieving any input (from the vid-cards...2d from mobo should work), or go in through software and un-sli your cards to get graphics on both monitors. Probably only an issue if you want to, say, game on one screen and watch dvds or something on the other.
The solution, as far as SLI is concerned, is to go with one of their dual-GPU offerings for one card, or get a bigger monitor and tile windows.
This fact, combined with nVidia's hit-or-miss approach to mobo development had me tearing out my hair for awhile.
Personally, I'm going for option "C" and buying the next-gen ATI chips (4xxx) series and an x48 mobo (saved myself some cash vs the 790 there) for crossfire later, if needed. If you're building sometime this month, and don't already have some of that hardware locked in, you might want to consider this option as well, especially if running 2 monitors is important to you.
I also prefer ATIs approach to vid card development...the GX2 and even the GTX can run very hot and consume quite a bit of power. ATI swapped over to 55nm process for their next-gen chips, and really payed attention to the power draw and thermal envelope this time around. I'm expecting good things from them this cycle, whereas all I'm expecting from nVidia is some power-devouring hot-spot of a GPU or two sandwiched together to out-benchmark the ATI offerings.
Don't get me wrong...I'm neither an ATI or a nVidia fanboy. I go with w/e is best on the market at the time I buy. I haven't even owned an ATI board yet. But I think they're going to win my support this go-round. Hopefully the pressure they exert, plus Intels grumblings about getting into the graphics business will make nVidia pull out all the stops in the near future.