If you are using a Motorola SB5101E on the Virgin network then you need to really change to Ethernet as USB connection has not been supported for almost 3 years.
Plus if you are using Vista then it will not work anyway.
The drivers are available on the Virgin site but are not supported by them and you can find them here.
http://www.virginmedia.com/help/broa...sb-drivers.php
If they do not work do not call support as they will be unable to offer support and will just advise you to upgrade to Ethernet.