well, i have a very similar setup and what i would do is get a nice big case, im getting the cm stacker if you can afford it. if you have room in your case get a dual 120mm fan radiator instead of a single 120mm version, cause that will cool better. get at leasst a 1 bay resovoir or some kind so that you dont have to worry about fill and bleed. try to save up or get the dangerden nvidia 6800 blocks as they cool the ram also but they are also 120$ each so if you need to save get normal vga blocks and most of those come with sinks for your ram on the card. i would also recomend since you are using sli like me this is my setup. get the dangerden rbx cpu block since it has 2 outputs. put each output to a seperat video card so they both hoave the colder water instead of daisy chaining them so one has colder than the ohte. then i owuld recomend a north/south bridge cooler as i think the fan on those is annoying and just get a y slipter from the video card outputs to go to that.
here is my setup
pump>radiator>cpu>Video Card 1 & 2> north\southbridge chip>resiovoir>pump
repeat