currently WoW does not take advantage of SLI/XFire, or atleast i can't find any hard evidence that it does. people say it does people say it doesn't and you know how that kind of thing goes... but anyway, just one GTX 260 should be more then enough to power your monitor and box WoW. the only problem though is that your 30" will be running at such a high resolution, if you wanted to add another monitor of just about any size, you would be maxing out the resolution output of your graphics card. this will result in drasticly lowering the performance of the card. so if you ever plan on running more monitors you should consider getting another graphics card. if you want this computer to be more of an all around better gaming computer you should get another of the exact same card so you can run them in SLI to increas performance in games like COD 1-5, Left for Dead, Crysis, FarCry 2 and all those other graphics intensive games with ~40 fps average.

what SLI/XFire does is it basicly combines multiple GPU's to produce higher performance. it also increases the resolution output of a single DVI/VGA monitor output, a must for soemthing like the TripleHead2Go. just do a quick google and you will find limitless info on what SLI/XFire is.

Hope this helps some. ^_^

~YYF