well, it depends on your budget as well as you Mobo socket type. this is the type of socket the cpu fits in, like LGA 774, socket 478 etc. we need to know that unless you want a new mobo.
Do you want AMD or Intel. im an Intel person, but you may not be.
Im not to sure on this, but putting a new CPU on an older acer mobo may raise some issues because you most likely have a locked BIOS, but i dont know if this will interfere with the installation of the CPU.
thank about cooling, the faster CPU may produce more heat than your case is made to cool.
And i just realized you have a LAPTOP. way to go me. Can you work on a laptop? cause that may make you want to build a desktop for better gaming. but if you want to keep your laptop, i strongly think you should contemplate how hard it will be to get to switching out the CPU, there will be alot of removal and it may be quite challenging. if you are experienced however, go ahead.
so yea, answer some of the necessary things and we may be able to help ya ;]
goood luck