Hi! If i buy a pb 12" today i only get a NVIDIA GeForce4 420 Go graphics card. I I would like to upgrad that card is it technically possible to that? I mean to put in a NVIDIA GeForce4 440 Go - 64 mb instead? I know you cant get it at applestore for the 12" model, but is it possible for a Mac technician to do it anyway or is it physically impossible due to hardware incompability such as standards (agp), space och power voltage?