I would also highly recommend upgrading the CPU to something which has multiple cores.
Even a used one is fine. Phenom II 965's can be had for $110 new, Athlon II x3's around $70.
Those will help greatly with new games.
Then as for GPU, 6670 GDDR5's are your first level of card to look at, they run about $80.
Then the next step up is 7770's at about $100.
Next step being 7850's at about $130.
the probably your best bet is to get a 6670, even a DDR3 version if you can find one for $70. Try to get a GDDR5 version if you can of course, but otherwise the the DDR3 version works too.
the probably your best bet is to get a 6670, even a DDR3 version if you can find one for $70. Try to get a GDDR5 version if you can of course, but otherwise the the DDR3 version works too.