Removable-media drives need not have media inserted for them to appear in the Drives collection.
The following code illustrates how to get the Drives collection and iterate the collection using the For Each...Next statement:
Function ShowDriveList
Dim fso, d, dc, s, n
Set fso = CreateObject("Scripting.FileSystemObject")
Set dc = fso.Drives
For Each d in dc
n = ""
s = s & d.DriveLetter & " - "
If d.DriveType = Remote Then
n = d.ShareName
ElseIf d.IsReady Then
n = d.VolumeName
End If
s = s & n & "<BR>"
Next
ShowDriveList = s
End Function