Do you need help learning how to overclock or are you having specific problems? There are guides here and all over the web on how to overclock a core 2 chip.
List full system specs and some questions about what problems your having.
I know how to overclock problem is when I raise the base clock to 241 and above it says please select proper boot device and reboot computer
BTW its not a C2D its a Pentium Dual Core