integrated webcam does not show up after win 7 reinstall

Hi 

I have reformatted many laptops mostly Inspiron 1545 1525 models with integrated webcams. I haven't gotten any of them to see the previously working webcam yet. I have reformatted the HD and gone thru and installed all the drivers associated with the associated Service Tag. They don't work or even show up under "my Computer" properties screen.

  Has anyone figured this out??

Thanks 

Steve