Don't confuse people, I am mining windows 7 with AMD drivers, I can switch to Ethash, Cyptonight smoothly. just use the proper driver and you will not have problem with it.
I didn't say the AMD drivers won't work in Windows 7, just that "Compute" mode won't be available, and, at least for me, enabling Compute mode bumped up my Ethash speed by about 1 MH/s (before the other stuff like O/C and BIOS modding, etc.).
If you want to use AMD cards *and* mine an Ethash coin (e.g. - Ethereum, Ubiq, Musicoin, etc.) then you'll want to move over to Win 10, otherwise don't bother.
suggesting people to don't bother on windows 7 for 1mh up speed, Lol, anyways its your take. the real Hashrates of AMD Cards will unleashed by modding them.