I have a very similar problem to you.
I bought a Toshiba Satellite Pro L850 (New Zealand model, can't seem to find a matching US model) and after a clean install of Windows 7 x64, this happened to me. I was able to install the ethernet driver and a few others, but I wasn't able to do anything about the graphics driver (like yours, an AMD Radeon HD 7670M). The only video driver detected in Device Manager is 'Standard VGA Graphics Adaptor'. Installing relevant drivers from the AMD website just results in a error message telling me my hardware is incompatible with their driver.
I'm basically stuck using my laptop without a graphics card, on 1024x768 resolution until I can find a fix, so if you find anything, please post it here so I can see and I'll do likewise.