Nevermind, I just realized you have a laptop.
First of all, you do NOT have a GTX460, you have a GTX460m, which is no where even close to the performance of a desktop GTX460.
This is a big project and would be very expensive. You have to take the entire laptop apart and remove the motherboard to replace the gpu.http://www.youtube.com/watch?v=Tp90M_N6dzs
If you want to play BF3 on ultra settings, get a desktop computer.