Video card suggestion? HD4850 vs HD5770

Hey,

So Im ordering a new video card because my 7600GT just aint cuttin' it anymore! Ha here is my current setup:

24" 1080p + 19" 1280x1024
AMD 2.6Ghz X2
2GB 800Mhz DDR2
Raptor HD

I would like to get a pretty decent video card to be future proof. Decided to go with ATI this time for their performance vs price right now. May even build a new computer soon.

So here are my two choices as of now:

4850

5770

For $25 more dollars, is it worth it to go to the 5770? Is my current setup holding this card back? Will the HD4850 be sufficient for the monitors I have?

Thanks!