Overclocking Intel Core 2 Duo

Solution
It's unlocked and will OC nicely if the BIOS in your MB supports overclocking. Almost all retail MBs will, none of the HP / DELL / Lenovo-IBM MBs will.

Plenty of guides out there. Google "overclocking core 2" http://www.overclockers.com/forums/showthread.php/515316-HOWTO-Overclock-C2Q-(Quads)-and-C2D-(Duals)-A-Guide-v1-1

https://www.youtube.com/watch?v=5KASgLl5GRg

Your MB may also support an upgrade CPU in the same socket. You can get a quad core on ebay used fairly cheaply. Make sure your MB and MB bios support the CPU you get.
It's unlocked and will OC nicely if the BIOS in your MB supports overclocking. Almost all retail MBs will, none of the HP / DELL / Lenovo-IBM MBs will.

Plenty of guides out there. Google "overclocking core 2" http://www.overclockers.com/forums/showthread.php/515316-HOWTO-Overclock-C2Q-(Quads)-and-C2D-(Duals)-A-Guide-v1-1

https://www.youtube.com/watch?v=5KASgLl5GRg

Your MB may also support an upgrade CPU in the same socket. You can get a quad core on ebay used fairly cheaply. Make sure your MB and MB bios support the CPU you get.
 
Solution
With a wide guess and some experience with core 2 overclocing, I would say you might reach somewhere between 3.3 and 3.6 GHz. Depending on your chip, cooling, build quality of motherboard and PSU and the speed your memory is able to run.

But of course be careful!
Read guides on how to oc the chip and test properly for stability (procedures should be mentioned in said guides)