Also, nagasama, SLI is not always worth it. For the smaller monitors with lower resolutions it will show very little boost if any at all. I have a 19" monitor at 1440x900 with my 9800GX2 (which is a pre-SLI'd set of 8800GTS as you probably already know) and it actually scores the same or barely higher than my 9600GT at that same resolution and got basically the same frame rates in Crysis and Call of Duty 4. SLI for small monitors IS NOT worth it. Pure overkill.
For smaller monitors, it would be better to get 1 good card over the two.
you misunderstand my point.
if you have a single card and a small screen and you come across another of your cards for say....20-30 dollars (like i did), its ALWAYS worth it. you will probably get a bigger screen at some point, right? most gamers do. i wasn't saying it was always worth it for framerates, i was saying if you find one at the right price, its ALWAYS a good idea to get it. when i added another 7900gs, my framerates jumped 20-30% and i only had a 19" monitor. which is why i totally disagree that it is "pure overkill" for SLI and a small monitor. depends on the card and numerous other factors. you tellin me that if you had a 7600gt and a 17" or 19" monitor, and found 7600gt's on clearance somewhere for 50 bucks it wouldn't be worth it? c'mon.
when i got a 22", they jumped 40%. then i got an 8800gt, and they were a little higher yet. then i got another 8800gt, and i really noticed mainly my cpu bottleneck, lol...but FPS went up a little. then i got a 24" and the 8800gts 512 i currently own, and it is about the same as the 8800gt SLI at higher resolution. when i come across a cheap 8800gts 512, i'll buy another one, you betcha.
to emphasize my point even better, use yourself for example...you surely didn't buy a 9800gx2 to use it on a 19" screen? i would assume you are planning on getting a larger monitor in the near future?
if it is "pure overkill" as you say, to have SLI on a small monitor, why do you have it (basically)?