Do you have a device under your printers that show up as an unknown device?
If so then you have to install the printer with the driver that you have, dont wory about getting it to work just yet just get the printer installed.
When that is done you have to figure out what port the Unknown device is on. Once you have that you need to go into the printer that you created and change the port for this printer to the port for the unsupported device. Then test by printing a test page.
If the Windows 7 driver is not available then try the Vista Driver. I work in IT and have to do this for some of the users.