before you overclock - do you have a way of seeing and monitoring the cpu temp from windows?
keep in mind - overclocking, if done properly, can yield significant gains in performance with little or no expenditure. you also run the risk of destroying your computer and certain expensive parts.
making sure your cpu doesn't get too hot is critical. in your bios you should be able to change the system bus speed. move it up in increments and use cpu-z to confirm your results in windows. run some demanding applications and/or leave the system running for a day or two to test for reliability. you may also want to change your multiplier setting, but do so in small increments. once you have either reached the point where the system will no longer run properly or are satisfied with the gains, you are done overclocking. good luck.