I have ENGTX295 nvidia but it reaches only 40 mhash/s on that wiki page it shows it can be 60,120 or more. for my graphic card . Drivers updated.
The GTX295 is at ~300w. If you want some bitcoins, it'd be cheaper to buy 1-2 now at lower prices.
Even at 120 mh/s, you'll be losing money at 300w (at current prices).