8800GTX overclocking help please?

I recently bought a XFX 8800GTX and worried about the temp of my card and so i downloaded Rivatuner as you do to increase my fan settings as because i play games quite loud don't have an issue sticking my fan on a 100%, but with playing around with my rivatuner i noticed an overclocking option and because i thought well coming to think about it my FarCry2 is lacking some framesPS so maybe my card will benefit from a little extra juice, so being a idiot i wacked everything to full and my screen crashed, so i rebooted and all the clocks went back to normal, but my question is how to overclock safely and make it work and will it give me my extra boost? i normally run my games on very high and high mixed with a resolution of 1600x1050 with anti-ali by 4x, running my system on a Antec Earthwatts 500W. P.S what considered a decent framerate and a GPU temp?

there are lots of good gpu overclocking guides out there that will walk you through it much better then me (i would highly recommend googling it and checking it out) but the basics are increasing each slider a little bit at a time and then running a program such as ATI tools + the Crysis benchmark and/or 3dmark06 to test it for stabillty (AKA no artifacts) until you can't push it any farther without getting the artifacts.