Laptops are not designed for upgrading the cpus. It may work, or not. If it doesn't, you're stuck with a cpu to unload. Even the cpu heatsink is difficult to change. Best to leave it alone and sell it intact to buy a new one.
If you want to try it anyway, check starmicro. Use cpuz to get the cpu serial number to compare with the replacement. Starmicro won't accept returns due to compatability issues. And you won't notice alot of difference in performance. For your next laptop, I would get windows 7 64 pro or ultimate with 4 gigs of ram.