Actually, most laptops do have a socket for upgrading the CPU, but it it is tough to open the laptop to upgrade it, and it isn't going to be worth it if you pay someone to do it.
I would recommend reformatting the system. That is probably why it is locking up. Often times people think their computer is getting "slow" then want to upgrade their computer when actually their operating system is getting all crapped up. After a year or two, or three, it's about time to reformat windows. It's just kinda the way it is. Things get messed up, drivers get conflicted, programs get added, removed, stuff like that.
If it's running windows xp, you are definately going to want 512 of ram in there. 256 mb is torture.
What you can try doing is defragging the system and running this neat app called
CCleaner. That clears up a sistem well.
