I want a 3.0 :C
In my experience, don't do it if you don't need to. You risk loving up the cpu and you'll have to buy a new one.
I have a Core 2 Duo 2.66 GHz, and one day I overclocked it to 2.8 GHz. I was playing Left 4 Dead 2, and on the finale it started stuttering, I thought it was just my system bugging up. Few seconds later, crashed. Turns out it overheated. Set it back to default clocks and haven't touched it since.
In other words: Don't do it. A light overclock of 0.05 GHz or something is fine, but otherwise, no.