Windows 7 has done a good job when it comes to identify devices, but many a times but it is possible only if the hardware is known to windows someway, but there are many scenarios when windows fails to find a device is listed as unknown Device in the Device Manager.
Now the pain begins when there are a couple of such devices them and since nothing is known we can keep finding and searching about it in round robin fashion.
Unknown Devices is a free application which helps you in finding out what exactly is the device by looking into the raw hardware details where manufacturers leave their signature and identifications.
When you launch this application, it lists down details of all the hardware connected with the computer. Next you can navigate to the Unknown devices list and expand it. In here, you will see two sections, one is Windows and Second is the database. Under Database, you should be able to find details about the hardware with high possibility of identifying the device.
If you are geeky enough, this software is not any magic but uses the Windows inbuilt calls to find such details. It is possible to find the hardware and Vendor ID manually and search into the PCI database to find driver, but the software above, makes the job lot easier.
I really wish this application had an option to export details into a text file. This would have made it lot easy for one to reach technical support in some way. As of now you can take screenshot and get the job done.