In addition to Onus's reply... I'm not sure how much that athlon 2 is but the 640 is 80.00... for about 10.00 more you can get a phenom II x4 965 which would perform better in games (the athlon 2's don't have an L3 cache at all where as the phenoms do)
the phenom II x4 965 is still regarded as a great value having good performance for the price.
edit: i was looking at the newegg.ca site which has the phenom II for 89.99 on sale right now... so it is 20.00 more at 99.99
What resolution? I would think no better than medium. A HD7750 isn't too much more expensive (make sure either one you get has GDDR5, not DDR3). Also, 2x4GB of RAM will give you better performance than 1x8GB; slight, but I think you will notice.
In addition to Onus's reply... I'm not sure how much that athlon 2 is but the 640 is 80.00... for about 10.00 more you can get a phenom II x4 965 which would perform better in games (the athlon 2's don't have an L3 cache at all where as the phenoms do)
the phenom II x4 965 is still regarded as a great value having good performance for the price.
edit: i was looking at the newegg.ca site which has the phenom II for 89.99 on sale right now... so it is 20.00 more at 99.99