what do you guys think? i've narrowed it down to the 8800 gts 512 sli and the 4850 cross fire. they are both great buys right now. i will be gamming with 20" monitor and might upgrade to a 24" next year. to be honest i'm leaning toward the 4850 in crossfire but i have seen the 8800 gts (G92) in action and it is awsome in sli. which will really get me better performance?

4850

definitely 2 x 8800 gtx.

Better drivers

huh?

hahahahah....

anyhow the the answer is 4850 CF.... X38 board costs less and performs better than Nvidia board... moreover you get two 4850's for just $300... and they quite comfortably outperform 8800GTS SLI

When single, g92 8800gts perform about the same as 4850.
http://www.techpowerup.com/reviews/MSI/HD_4850/10.html

G92 8800gts sli:

Pro:
-Cheap. A g92 8800gts cost $120 after mir, compared to $200 for 4850.
http://fxvideocards.com/ZOTAC-GeFo [...] 16280.html
-Cool running. Usually does not exceed 65C on max load.
-Overclocks well, typically 20-25% core clock increase.

Con:
-Sli requires Nvidia chipset motherboard, which is expensive, runs hot, and performs badly.
-Does not support directx10.1, only dx10.

Hd4850:

Pro:
-Support directx10.1
-Crossfire requires x38/48 chipset motherboard, which runs cool, performs well, and is moderately priced. (P45 is not recommended due to pcie2.0x8 cf mode bottlenecking)
http://www.tweaktown.com/articles/ [...] index.html
-Scales well as resolution increases. The higher resolution you run, the higher 4850's performance is relative to comparable cards.

Con:
-Runs hot. Temperatures are usually 85+C idle.
-Overclocks badly.
-Cost more.

The 8800GTS 512 doesn't typically OC 20-25%. While there are cards that have broken the 800 core barrier, that's not really all that common. The typical OC on an 8800GTS 512 is more like 15-20%, which brings the core up to 750-780mhz.

i have a 4850 and did a mild OC to 650/1050 and sped up the fan and under a load it never went higher than 66C.

ran crysis on very high with ~30fps. so it was playable.
completely maxed out cod4 with 90+ fps.

and drivers are very new for it and crossfire technology is getting better faster, imo. i'm not entirely impressed with SLI lately.

i would DEFINITELY go with the 4850s because
-cheaper/better motherboards will support it (~ $100)
-better overall performance from the 4850s, especially at really high settings. the 4850s will last you longer in terms of next gen games etc
-you can fix the fan so they won't run hot
-drivers will improve and therefore the cards will perform better/crossfire will scale better. the drivers for the 8800s aren't really going to get radically improved.
-basically the same price for the cards.

go with the 4850s thats what i'm did and i don't regret it.

Overall, I'd say that the 4850 will yield you better performance; the results in the article dagger linked are known to be anomalous to the overall performance of the 4850, where it single-handedly bests every G80 and G92-based board, excepting, of course, anything with two GPUs. This actually even includes the supposedly ATi-hostile Crysis, where you see significantly different results from TechPowerUp's article from Tom's themselves, in spite of the slew of rumors that Tom's supposedly favors nVidia. There, we see that the 4850 trumps every G80/G92 with AA/AF enabled, save for at 2560x1600, where the only non-GTX200 card to get ANYTHING, the 8800ultra, got 2.9 fps, which was still entirely unplayable anyway.

To think on it one way, SLi 8800GT is only a bit better than a SINGLE 4870, with the 4870 usually showing a 20-25% lead in benchmarks over its slower sibling. So yeah, overall, it should yield you superior performance; this seems to also strongly continue into CrossFire, where it appears that at higher resolutions, the 4850 has a rather high level of efficiency in CrossFire.

Also, it's worth noting that price-wise, the 8800GTS has little to no point, since on NewEgg, both cards start at the same $170US, with the cheap Radeons including a Sapphire-branded card, (eVGA's counterpart for Radeon cards) while the inexpensive GeForce cards are limited to GIGABYTE and ECS Elitegroup, which are both decent, but not quite as good as eVGA or Sapphire.

Also, perhaps it deserves a mention that with a pair of 4850s with one-slot coolers, they're going to be dumping a fair amount of heat into your case; 220 watts or so, comparable to a Pentium 4 Prescott. So if you go with them, (due to better performance and, knowing how Intel's chipsets are cheaper than nVidia's, a lower motherboard price, too) do keep in mind that you should pay some attention to the airflow within your case, so it doesn't overheat.