i wasn't done posting yet....accidently hit post now...lame.
As jay beet me to it, that is how you will actually go about OCing your machine. For a much more complete overclock guide go ready the sticky in the overclocking section. If you are new to Overclocking you should most defenatally read it before attempting anything. If you have some idea of what you are doing then here are some of the basics for overclocking and some things to consider (note that this is by no means everything there is to overclocking, as i said before if this is your first time overclocking you should go read the sticky)
You can set your FSB to 375 and the multiplier to 8 to achieve 3.0 gzh overclock but also run your ram at 750, which is of course faster then 667.
When you are actually overclocking your system i would leave your voltages on auto until you make sure your overclock is stable at 3.0 and then start lowering the vcore and ram timings until it becomes unstable, but that is just my personal preference for small overclocks. You could totally start low and increase the voltages manually with the overclock as Jay said.
To test for stability run Prime95 for 8+ hours, along with real temp to monitor the temps of your processors (core 1, core 2, etc.) Your processor should be idling in the 30's, maybe the low 40's, and shouldn't get above 65 or so under full load.
Hope this helps and post back with any questions or concerns
Edit: Changed to shouldn't get above 65 instead of should get above 65... only a tiny bit important
Edit 2: Added some information i missed on the first go around