If you are adding a device/accessory to Windows Vista and you are getting an error about it being an "unknown device", Vista is not finding a device driver. This has happened to me twice now, even though the driver was there on my computer. If this happens to you, here's how I got it to work.

First, plug in the device. This will bring up the Vista "new hardware found" wizard. Go through the steps to automatically install the device. If it fails when it is searching for a driver, it'll give you a chance to enter the path where the driver lives. Enter the following path: C:\Windows\System32 and click the box that allows it to search the subfolders, then hit Next. For both devices where I had the error about the driver not being found, it was found when I searched in this folder.

If you search in this folder and the device driver is still not found, your only hope is to search for it on the Internet. Just go to Google and enter the name and model number of the device followed by "Vista driver" (without the quotes). Unless this is some really obscure device or a driver just doesn't exist, this should get you to the device driver you need. Download the driver to your computer, it may be zipped in which case you'll need to unzip it before it can be used. Once you have the unzipped driver go through the new hardware wizard again (unplug the device and then plug it back in if the wizard is gone) and this time enter the folder that contains the driver you downloaded.