If you run a Geforce 7xxx, i recommend highly to replace the standard nvidia cooler&fan. It hass not to be that expensive but makes it A LOT quieter and well, cooler
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Having run the safe Nvidia-nTune-overclocking test run (4 hours-run), I now have to profiles, one with the stock settings and one overclocked, and I've set custom rules which enable the overclocked one when the PC is working hard for more than 30 secs, and returning to the stock one during "easy" jobs. Quite fancy this way, If running graphical harmless 2D apps I'm unable to hear my graphic card fan (autocontroled) and have the ~10-15% power plus from overclock when running a game or else.
I suggest the Arctic Cooling sets, they have detailed instructions on how to change the fan without killing the graphic card, have a very good perfomance and are not that expensive (10-20€, depends on graphic card type).
Of course you should have some basic idea how you have to handle sensitive electronic devices (no, you don't need the big hammer or the drill...) and ABSOLUTELY NEVER EVER use brute force when something doesn't fit. Just stop, take a brief look in the instructions and what you have done and search the error. You never need force with electronics. It may fit eventually, but there's a 90% chance you killed your device^^ .