Not supported scanner driver Windows 7 , Windows 8

If you have an older scanner, which is not supported by Window 7 or Windows 8, you can find useful the VueScan Scanner Software program.
This helped e.g. using of HP ScanJet 3500C scanner on Windows 8.

The program costs about 40 USD.
Website: http://www.hamrick.com/
Supported scanners list is here.