A program i know of is EasyTune, this can be used for Gigabyte motherboards.  You need to check your motherboard to make sure it can o/c, most likely will (some very cheap ones don't).  Then say to yourself do i need my warranty, then is this my comp, then can i afford to replace it if it breaks.  If you pass those questions you may carry-on.  If you have a temperature measuring probe you can see if it gets too hot.  I would recommend finding out your limit for that cpu.  Upgrading the HSF will help you.  Also if it is possible set-up your bios to cut the power to the cpu if it goes beyond a certain temperature just incase you take it too far.  Then boot-up the program and set it to go to a certain Mhz you want say 600Mhz then set the program running it will do it gradually.  I am not sure how much you will get out of that cpu.  ONCE THE CPU GOES BEYOND WHAT IT CAN TAKE IT WILL NOT RETURN, IT IS DEAD, IT GOES WITH NO WARNING!

When i Gigabyte i mean the manufacturer.  That is the motherboard manufacturer i use.  You will have to look around for the one for you.  Easytune may work for you i am not sure if it works with other boards but i am not sure.

Take the power cable out of the back.  Open the case up look at the mobo.  There should be a manufacturer name or number on it.  Mine is just above the RAM slots and slightly left, near my processor.