Changing the CPU probably won't give you the benefit that you are hoping for. Looking at the spec of that model laptop, if it is still standard you would be much better replacing the 5400pm 160gb drive in there. If you replace the HDD with an SSD the performance gain would be massive, especially from a 5400rpm model. Also I think that machine only comes with 2GB RAM as standard. An upgrade to 4GB would likely see a measurable performance gain also. These things can be done relatively cheaply and don't involve major laptop surgery.