Re: Refresh Rate.???
You won't really get a performance increase by having it higher or lower.
In games though, if you have Vertical Sync on, and your monitor is set to 75hz for example, yet, your card could power the game with 80+ frames, then setting your monitor to 80hz will allow you to see more frames that the card is producing, yet at 75hz, your card is forced to render 75 frames per second (which should be smooth anyway)
Setting Vertical sync to off in games allows the card to render as fast as it can produce, though the monitor if set to 75hz for example, won't be seeing all the frames the card is producing if the game can render higher than that. This can result in a banding effect.
But answering the question, 75hz is fine, and if you have a CRT, your not likely to see the refresh at this rate. Though if it can go higher, you might as well try it, and test the results with your eyes.
Abit IP35 Pro / Q6600 G0 / Zalman 9700 / 8800GTS 640mb / 4x 2GB Corsair XMS / X-FI Xtreme M / 1x 1TB / Antec 900 / Logitech Z-5500 / Samsung 20inch