Not in sync with Microsofts idea for Windows 10 users, I procured some initiative of my own and not 5 minutes later I obtained the latest Windows 7 (yes, VII, or winver 6.1) WHQL'ed drivers for the 7900 GTX via Nvidias website www.geforce.com, made sure it had the right bitness and clicked on setup. Another minute later I was ready to roll. The driver works like a charm from what I could see after 5 minutes of toying around, even though it was in no way meant for Windows 10. Desktop resolution, UI accelleration and simple 3D games - it's a DX9 card after all - worked.
It's quite slow by todays measures and it is not what I would call feature packed. But for basic desktop tasks as well as for some simple games it still can be used - and the ability to drive most displays at their native resolutions is a very tangible improvement over Microsofts Basic Display Adapter even if the card is only there to bridge a temporal gap until the new, massively shadery 3d accelerator arrives.
I didn't try explicitly, but I could very well imagine that a similar approach would work pretty nicely for AMD cards as well.
So, there you have it: Don't despair, don't believe the driver archives and show some initiative!