To Ruud, Just so that you know, I have gone down the route of using
 Code:
Dim $net
$net = CreateObject("wscript.network")
$net.SetDefaultPrinter($ServerName + "\" + $printsetup) 
etc etc etc


so I am not too fussed about the setdefaultprinter bug as only affects one old program, which is only used by one or two of my clients. However, having said that, as the function is not matching what happens when you manually set the printer - i.e. the correct case is entered into the registry, it probably makes sense to fix it so it does exactly what the manual setting does.
Thanks Rob