Help! Toshiba C50D-A Missing Windows 7 Drivers

I've recently purchased a Satellite C50D-A-11Q and back-spec'd it to Windows 7 64 bit. Unfortunately; there are two drivers which, despite hours of searching, I cannot find. One is the Universal Serial Bus (USB) Controller and the other is the graphics driver. I've been in device manager and discovered that the Graphics Chipset is an AMD Radeon HD 7310 and the USB Controller is an AMD FCH USB XHCI Controller. However the correct drivers still elude me. Any suggestions gratefully received.