The GeForce 5600 is quite an old card, I doubt there was a Windows 7 driver released for it, I also doubt there were 64 bit drivers made for that card either, so if you are running 64 bit Windows 7 you are out of luck. If you are running 32 bit Windows 7 and there happens to be a 32 bit Windows Vista driver available for your card you may be able to use that, if not you are either going to need to upgrade to a newer card or use the default video driver that comes with Windows. If you do use the default driver though, you will most likely run into issues if you want to use the more advanced features of your card like rendering 3D graphics.