It's up to you...remember if you overclock you will void warranties. Also, unless you know how to OC, I wouldn't reconmmend doing it, as it can bring you loads of trouble.
But if you really want to, just raise the FSB very slowly, like by 1mhz at a time, and see if the system is stable. You only need to raise the Vcore if the OC isn't stable, but do not raise it by too much, as more voltage = more heat. In addition, if you have a bad OCing motherboard or ram, especially generic, you might not get far at all.
edit: wohoo 3,000th post!