Take a couple more safety precautions and feel around your components, if everything, and I mean EVERYTHING is cool(not overheating)It's up to you to take the next step, if you think everything is O.K. and your system will handle it, go for it!
ONE THING YOU HAVE TO MAKE DAMN SURE NOT TO OVER HEAT IS YOUR CHIPSET, THE ONE WITH THE HEATSINK ON IT RIGHT NEXT TO YOUR AGP SLOT BELOW THE PROCESSOR.
Make sure it is not too hot before proceeding...
Please be carefull, and have fun overclocking!