All video cards carry some power supply requirement. You might be fine with that power supply as the 7600GT requires very little power compared to other GPUs. From what I've read, it's probably the best and requires the least power out of any "decent" GPU you can get at the moment.
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Primary- i7 920 | 6GB RAM | 9800GT | 160+160+500GB
Secondary- Athlon X2 4200 | 2GB RAM | 7600GT | 80+250GB
Netbook - Atom N280 | 2GB RAM | GMA945| 160GB
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