Expensive stuff, static.

[kinmel]

My old one was an HD4850, so the upgrade had to be a   XFX HD5770  

[Technical Ben]

Nice. Pity the old one died, else I'd buy it as a second to mine. The 5770 is on par. Slightly slower in the clock speeds, but makes up with better architecture. (or visa versa, I forget which).
Basically, the 4850 is close to the top of the range on last years model, and the 5770 is mid range of this years model. But the performance increase this year makes up for it.