Since you already have a 5850, watch prices in coming days, because the 5 series will probably be price lowered, and their production stopped.
They are produced on the same 40nm technology wafers, and the 6 series is going to be cheaper for them to make.
So I would keep your options to AMD choices unless you want things Nvidia offers, physX ,cuda , their 3d. Nvidia drives.
If you sell your current 5850, which alot of people can't or won't do, you could do the gtx 460's or AMD 6850/70
Or the cheapest route, buy a 5850 thats marked down in coming days. Which will give you NICE performance.
1) Keep it and wait until the prices drop on the HD 5850s if you do not plan on looking at the 6800 series.
2) GTX 460 1GBs are not ~$200 pending the release of the 6800 series. The 6800 scale just as well as the GTX 460. If you do plan on selling the HD 5850, the HD 6850 in xFire is the way to go.
3) For the 5800 series, probably not. It's not like the scaling was extremely bad to begin with. However, the 6850 scales very nicely and is much cheaper and saves a lot more power. They are the no-brainer in your situation (other than the HD 6870).
And quite honestly, any of the three (6850/5850/GTX460) in xfire/SLI will serve you well for a good amount of time with your resolution.
I actually don't recommend the 5850... I loved it, loved it for its OCing potential and Single card performance. But right now. At the price, Nvidia really can't beat the 6850. It's out on Newegg right now! Only 180$ for a single card... HECKA CHEAP compared to GTX 460. I mean expect a counter. But look at this benchmark of its CF performance. Now imagine the OC'd CF performance!
Well if the 5850 was still 300$ I'd rather get 2 6850s since the price is practically the same only 60$. Less pwr consumption, great performance, new tech, better "tesselation and DX11" perf according to AMD slides. Plus that's probably where all the money for drivers on the 5xxx series went.
Thanks for all your input...Dam, I didn't realize this 68xx were out when i posted. If im gonna drop this much $ anyway why not get the 6870s? Would it be worth waiting for custom cooling ones to come out or are the references cool enough with this gpu? Also... Im sure i wont be able to sell my 5850 for much now.
Do we only have ATIs slide for benchmarking to go off of?
Gotcha, based on that review it looks like the 5850 still performs slightly better than the 6850 - so 5850 since i have one? Either way ill prob wait for the holiday season to come and the price wars to start... should be fun : D