First off, on the m15x yes you can change out the graphics card and that was one of the purposes of it being custom before they got bought out by Dell. I still have one I use as a media server running an mobile version of the GTX8800. There is a GT9800m version that will work on the m15x that would run most modern games at a screen res of about 1366x768. However if you have 1920x1200 screen like my old one it will have a hard time with some games. There is also an ATI card for the MXM socket on that model that is even faster but I don't recall the model. It is still a good laptop but it is going to cost you probably more in card than it is worth.