Need advice for budget upgrade from 4850/1gb

Hello,

i am considering upgrading some parts as my system doesn't really have enough juice for more recent games anymore

My current specs:
Asus M4A78T-E
Athlon II X3 445 black
MSI radeon 4850/1gb
target resolution 1680x1050 on primary monitor, occasionally 1080p on the tv
8GB RAM

I am on a tight budget, so i would prefer to keep the upgrade cost below 120€/150$ roughly.

One candidate to replace would be my graphics card, i looked around a bit and the things that looked promising were the 6850 and the 7770 at about the same price of 120€/150$, most cards below that seem don't seem to offer a significant enough boost to warrant the expense.

With that in mind, i am not quite sure if it would not make more sense to switch my cpu instead. Candidates here include the Athlon II X4 631 which is available for around 50€/60$ and seems to be quite good value for the money (going from pure benchmark scores it seems to offer a boost of around 55% compared to my current one), or one of the cheaper phenom IIs for around 80€/100$ like the phenom II X4 945/965

Any advice one way or the other as well as better choices for both would be much appreciated