Intel Dual Core 2.4ghz to Intel Dual Core 3,4ghz

What are the two CPUs, and what motherboard do you have? Installing the faster one may just be a matter of dropping it in, but if the new one has a much higher TDP you'd want to be sure the mobo would handle it. You would also probably need to reset any overclock. This of course assumes the two CPUs go in the same socket...