5805 for 2 5770?

Yeah, slight performance increase but nothing worth the spending money and the hassle of doing the upgrade and dealing with crossfire.
Have you overclocked the HD5850? They tend to OC very well and you can get an equivalent performance boost that way for free without any crossfire scaling/profile issues.

well thing is right its like a $20 price extra for the 5770s, and online I see that its performance is on par with that of a 5870, and the 5870 out performs the 5850 by far...

oo ya anf i love working on my pc, and changing things up a little, but im stil not sure its the right choice coz my friend wants me to get him a GPU and i can make a bit of cash, or sell him mine and get the 5770s? wich should i do

also starting to feel a bit disapionted in my 5850, not performing the way I was hoping, it cant run Lost Planet 2 on full graphics, even with no AA, I have to run on meduim for comfortable game play

The HD5870 is 15-20% faster than the HD5850. While crossfired HD5770s are roughly on par with an HD5870 in average frame rates the minimum frame rate(which is what matters to play a game smoothly) suffers in comparison.
With overclocking taken into account the performance difference will be negligible. If offered an HD5850 or two HD5770 I would take the HD5850. If you want an upgrade the look elsewhere. Perhaps an HD6950 or GTX 560 Ti.

With the 5770's you drop down to a 128 bit memory interface so when things get tough you start to notice the limitations of the card (even if using 2 of them you will have to turn down the settings to keep performance smooth) -- keep the 5850 and save up and get a 2nd 5850 if needed later -- getting the 2 5770's might get you a bit of extra performance now but you then limit your options once they get limited and you want another bit of increase while the 5850 still has the potential to xfire it and get a new level of performance when needed for only a small cost !