Originally Posted by GibsonSGKing
5770's are better in most cases, but if you get an HD5850 you can add a second later and have a crazy set up.
I might not be a techie, but the answers you're getting are for here and now, and you don't wanna look at that.
If you get 2x 5770s, then that's it, you can't add more, you'll have to replace the cards entirely when you next upgrade. If you get a 5850, then you can get a second 5850 down the road when 1x 5850 isn't enough for you.
2x 5770s may give you a bit more power RIGHT NOW, but 1x 5850 will serve you better in the longrun and will be altogether a better investment.
Besides, you'll be able to game to your hearts content either way, they're both safe choices.