I think you have to determine whats holding you back right now.
The X2 4800+ and the whole 939/DDR architecture is maybe the bottleneck in your system right now. If it is, you'll gain very little by upgrading your GPU.
really good i haven't found a game that i can't really play i get 60fps with far cry 2 on med settings and S.t.a.l.k.e.r. ClearSky around 52-54, what about hese cards
as I said, you need to figure out first if it's your CPU/system or your GPU that holding you back.
If it is your GPU, then it is a matter of googling for reviews/benchmarks that will compare performance of those cards at 1680X1050.
You'll find out then if it's worth the upgrade considering the price. In my opinion, you have a well balanced rig right now, nut I'm no expert in gaming performance.
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