Rather than map yet another drive designator to a UNC (universal naming
convention) for a shared resource, why not just the UNC?
How to connect to network resources in Windows XP without mapping a
drive or a port
http://support.microsoft.com/?id=311079
The drive letter makes for a conveniently short designator to the shared
resource but it isn't mandatory. After all, the drive designator is
merely providing a shortcut to the UNC (i.e., it is a convenience to
you, not to the computer). In fact, there are times when you might only
want to access a shared resource once or twice and don't want to go
through all the hassle of defining a mapped drive designator for it.