I feel like not enough people know about this, but Windows versions that are built on NT6, which is right now Vista, 7, and 8, all have the same driver framework. So in reality, if a driver works for any one of these OS's, it has a very good chance of working on another. In fact, you often see drivers from the major vendors have a version for Vista/7/8, not because there's three of them in there, but because one driver works for all three (otherwise, why not throw in XP?). If you don't believe me, download NVIDIA's drivers, and run it until you get to the actual install procedure and cancel out. Look in C:\NVIDIA\DisplayDriver\[version]\Win8_WinVista_Win7_64\English\Display.Driver. You'll only find one set of drivers in there.
So while it's preferable to use drivers for the OS you're using, if you can't find one specifically for the Windows flavor you're using, another flavor may work just fine.
I've also had some luck with XP drivers working in Vista and 7 in the past by force installing through Device Manager. But I don't believe this works for all devices, and in this case it was for a WiFi receiver.