4GB is plenty for the vast majority of people out there. Very few programs will use anywhere near that amount and games definitely won't.
For pure gaming, I'd drop to a Pentium G600 or G800 series to free up a little more money for the graphics card. I'd much, much rather have a G640 with a 7850 vs a i3-3220 and 6850.
If you are in the US, newegg has an XFX 7850 1GB for $141 after rebate through the weekend.