The only thing I'm not sure about is how SLI affects "standard apps (PS, etc.)", when it comes to multiple displays.
What I am saying is that ... I am ABSOLUTELY certain that you can run up to 4 mons on those two cards IF THEY ARE *NOT* SLI'd ... Nvidia drivers (and Win7 Native!) will find any nVidia cards and let you "gang" displays in a number of ways.
. . . I am also saying that I am NOT AT ALL certain how the SLI connection effects the multi-monitor options in a non-gaming environment. I would very much like to know this!
It IS really nice to have the extra screen real-estate when working with bins of thumbnails and navigating directories (on the side) while working with graphics or video or music timelines, etc, in the main (2xDisplay) workspace, etc. ... Any sort of content creation workflow will benefit greatly by use of more display space.