I was able to get a S510M that is marketed towards to Apple Mac users to work on Windows 7 by loading the latest ScanSnap software for Fujitsu for the S510. Once loaded and patched to the latest version, hook up via USB to the Windows 7 computer.
When I did this I got an error that no driver was available, but I went to Computer > Manage > System Tools > Device Manager and right mouse clicked on the Unknown device for the scanner. Choose Properties and then the Driver tab. Click Update Driver ... and then manually select the Fujitsu S510 driver to apply to this device. You should get a warning message saying it might not work but say OK.
Once that drive was applied to the Device the S510M (with S510 driver) showed up in the Imaging device area and scanning worked without any issues.