AMD had trouble absorbing / integrating ATI, and the companies were like long lost siblings in many regards, from the rather significant disabilities in handling business processes and the disdain for most things software, to the engineering prowess and the "if you build it they will come by magic" attitude. Also the constant whining about the evil competitors that always win through some dastardly scheme as opposed to based on some merit. NVIDIA would've caused a huge indigestion, not to mention what is likely to have constituted a bleed that would make Rory's clean-up seem like a bit of nose powdering, once Jen-Hsun would've started actually expecting results from old school AMDers that were accustomed with the "slow and possibly stagnant wins the race...or at least minimises stress" attitude.
Conversely, NVIDIA integrating AMD would've hugely strained their resources, at a time in which NV needed them. So I disagree with the notion that it was likely to have been a good deal, it would probably have been an equally bad one, but it is possible that JHH would have been better at not completely screwing things up, contrary to people like Ruiz or Meyer, who were quite obviously deprived of any strategic vision, tenacity or even intuition. Meyer's backing of BD at all costs was quite clearly highly detrimental to AMD. Considering the ludicrous amounts of sales it brought (and it was clear once they actually got silicon / advanced sim results back that it would suck, please no JohnFruehe mentions at this point), AMD would have been better served just selling K8L, possibly using the tweaked core from Llano and dragging on until they could release Trinity based notebook SKUs, which is where that chip could have done serious damage. Instead they blew large amounts of money bringing up and marketing a POS - JHH and/or possibly even RR would've just said no, Meyer went for it.
AMD could've gotten S3 or XGI for pocket change, coupled with SiS remaining chipset engineers, and thus they would've gotten their miniME Intel platform. They also would have had a large chunk of money to invest in their core business and in process R&D (maybe 32nm wouldn't have sucked so epically as a consequence? since GF's current 32nm is pretty much inherited from AMD). Hell, they could have done what everybody else is doing with them currently: wait for ATI's carcass to hit the ground then pick it up, as opposed to ridiculously overpaying for it as if it was a company in full stride. Which it definitely was not since ATI had had a pretty fubard margin model, and botched up releases for quite a while.