When I get a lappie in here that's dragging its tail, I simply take off user data, wipe the driver and reinstall the OS from a OEM DVD and register with his original key code number....download appropriate drivers, copy back the data and give it back.
The other thing is that in order to hit their price points and look better than their competition, they will advertise the CPU, GPU and RAM say, and then don't mention the crappy 5400 rpm HD that they thrre in to offset the cost of that stuff.