You're unlikely to see any difference at all (by human standards) from an under 10% overclock.
Assuming you have decent airflow to your case and a decent aftermarket cooler, you will hit 3.5 GHz in your sleep.
As a start, there are a few things you will want to install if you haven't already:
Intel Burn Test or LinX (same thing, IBT is probably easier to find online)
Core temp or Real temp
After getting those, I would seriously recommend finding as many guides as you can, people here will be able to tell you what to do, but to be able to OC properly and safely you need to read lots of info.
Take everything you read with a pinch of salt and do your very best to know what everything in your BIOS does, anything on auto is potentially a risk
The motherboard BIOS manual can be a good place to start btw.
Thought I should point out, it's a misconception I had starting out OC'ing, and I know I'm not alone.
Running a lower voltage than is needed to be fully stable damages the chip far more than the additional voltage would (within reason). Every error causes degradation of the chip, so a couple of minor errors a day, can seriously reduce the lifespan of a chip.
I don't want to put you off, but make sure it's fully stable and don't skimp on voltage (though that's not to say you should nuke it with voltage, bump it up reasonably with small increments)Edited by Crabid - 3/9/11 at 4:33pm