Upgrading HD4850 Budget under $250

SnS

Honorable
Jan 22, 2013
8
0
10,510
I was wondering what would be a good upgrade for me. I wouldn't want to buy something that would just bottleneck anything I have now. Any thoughts would be helpful. Thanks

I currently have:

Athon II x3 450
EMX-MCP61D3-iCAFE - mobo
Powercolor HD 4850
8gig ram
550w true rated psu (Forgot the brand)

btw: Can I go for R7 or R9?