nachowarrior :
considering most people choke their cases on air supply, i'd hit the 4890, it's a good idea to have plenty of air flow anyway for longevity of your parts. Ati's new drivers for win7 work great so far, even my old 3870 got a kick in the pants on performance over win xp x64 drivers. 😛 also, gpgpu computing on ati is enabled in win 7, another thought. 4890 is great single card, especially at higher resolutions. two smaller cards would be fine but i see two issues with that, one. correct me if i'm wrong, but that 790x platform is 8x and 8x on the pcie with two cards, not a HUGE deal should work great, untill you hit 2x massive cards. a single better card is generally better performing at higher resolutions than 2x smaller cards. Keep in mind your memory allocation when using large monitors, generally 24" or using two monitors. 1680x1050 i think gets GREAT benchies out of 2x 4770's in crysis vs the high end cards, whereas the 4890 pulls ahead when you get to the higher resolutions. Something to keep in mind as well. Having said all of that, I prefer the 4890. the 260 will (in some games) have you regretting not getting the 4890.
In fact, this mobo has 2 PCI-E 16x slots, one running at x16 and the other one at x8. In any way, it is not my intention to have 2 graphics cards bundled with SLI or xfire, and I will stay with one card only.
I am still undecided about which GPU to choose. I am looking for reviews of each GPU made by the same reviewer or under the same conditions so that I can compare the performances.
I think I will be fine with the GTX 260 as far as robustness and stability of the drivers are concerned. If the 4890 is superior in terms of performance, I would like to know how much superior it is really, and that is why I am looking for appropriate reviews or or product comparison reports of both GPUs.