Sometimes your computers may fall behind in the speed department, may lock up or just fail to deliver like they used to. Truth is, most laptops have a stock 5400rpm HDD with little to no cache. When they begin to fail, they go from being slow to even more slow, until they completely fail.
Believe it or not, if your laptop still has DDR2 ram in it, it is still viable! Just replace that dying HDD with a 7200rpm HDD that also has a decent cache size and increase the ram in your laptop. A fresh OS install with your docs, pics, music, favs, desktop, and downloads will remind you that your laptop is still quite fast! (make sure your technician cleans the old thermal paste and pads from the chips and cooling setup, replaces them, and cleans the dust from the heatsink!)