Finally solved this with a colleague. Actually nothing wrong with the card or the drivers but a problem with the registry. See the comphrehensive solution at
http://support.microsoft.com/kb/810509
Took seconds to download and fix (tiny file). And in case you have to work it out like us, the command is pnpreg -l which is a little 'L' not a '1'.
Hope this helps others and thanks for all your help to date.