a Q6600 (2,4ghz) wil easily overclock to 3,0 without a voltage increase.
So your Q8200 will be easy.
Overclocking options is in your bios.
You should change the frequency and watch your memory.
You can unlock your memory multiplier (probably) or set it a fixed ratio 2:1 1.25:1 etc
You don't need to touch the multiplier option. Just change the front side bus (FSB)
But be carefull not to go too high, most bios have a preview of what the clockspeed will be like.
a q6600 @2,4ghz has a FSB of 333mhz (:memory: 677mhz) you can set it to 400 and your memory will overclock to 800MHz. Depending on your multiplier (8 or 9 will result in a 3,2ghz overclock or 3,6 (multiplier x FSB)
But I would suggest a mild overclock to start with, since I don't know what cooling you have!
Also you can download prime 95 multicore (testing maximum temperature)
And download coretemp to look at your temperature when you overclock.
But I currently have my Q6600 at 3,0ghz.
To do this you need to change the following:
Change your FSB Front side bus, to 356mhz
This will overclock your memory to (712mhz)
You can leave everything auto, and it should boot up effortlessly.
Just make sure you test with prime 95 and watch your temperatures!