Targetting 8-10 boxing single CPU

[kaiverrettu]

Hey, im trying to reach my target of 8-10 box. Atm im running around with

i7 920
12gb ram

Now im looking forward to upgrading my crappy graphics card but im thinking, should I save some and buy a 200$ one instead of say, 150$ one(such as the 6850) to increase my boxing capacity to the max? Could crappy graphics card make the difference and allow me to box a few extra toons, or should I look forward to upgrading my CPU to 960 instead, or buying more RAM?

Mostly concerned about the bottleneck here - I don't want my GFX to become the bottleneck in my system. Thanks.