I was looking at upgrading my graphics card from a 9600GT to a Radeon HD 4850. Its an older system with a Core2Duo. For the money it seems like a good deal, any thoughts.
You can probably find much better deals on the buy/sell/trade section. For instance right now I'm selling a 4870 for $65. If you scout around you may find a 4850 for $50.
You probably wouldn't be able to find a brand new 5770 for that price, you have to look around at someone selling used. Anything new probably wouldn't be under $100, it's a good card though, well worth the money. I got a new Sapphire 5770 Vapor-X for $110 to upgrade from an 8800GTX and it was well worth the little extra money I was willing to spend. (I was also looking for a 4850/4870 like you were).
I'd look around at the buy/sell/trade section to see if anyone's offering something used.