This is just formal notification caused by that the installed driver has not Microsoft® digital certificate and as the result may not have "Designed For Microsoft Windows XP" logo, is absent in the Microsoft® WHQL driver base, is not distributed and could not be installed by Windows Update system.
Microsoft® digital certificate is not obligatory. New driver versions are distributed through the web-site of official Beholder® company's web-site. All drivers are thoroughly tested in all Windows operating systems and their correct work may be guaranteed only by device manufacturer for that the driver was designed, and that is assured by by Beholder International Ltd digital certificate, that is necessary for driver installation under 64-bit versions of OS Vista and server versions of OS.
When this message appears you need to choose «Continue anyway». If such option is absent in the message window, you need to allow installation of unsubscribed drivers. For this click "Properties" on "My Computer", select "Hardware" tab, click "Driver signing" and in opened window select "Ignore – …" or "Warn – …". After accepting changes by "OK" open device manager, find unknown device with the name "Multimedia Controller" in group "Sound, video and game controllers", and in context menu of this device select "Update driver…", then repeat driver installation procedure.