There may be situation when a driver for upgrade operating system is not available e.g. driver for any old printer which available for Windows XP but not available for Vista or Windows 7.

In such a case the old driver can be used / run on new os with compatibility mode setting.

right click on the fils setup.exe or similar file click to compability tab and set compatibility for the oS of which the driver exactly belongs. thereafter run the setup and it will work on new OS also.