En un módulo declarar :

Declare Function GetVolumeInformation& Lib "kernel32" Alias "GetVolumeInformationA"
      (ByVal lpRootPathName As String, ByVal pVolumeNameBuffer As String, ByVal nVolumeNameSize As Long, lpVolumeSerialNumber As Long, lpMaximumComponentLength As Long, lpFileSystemFlags As Long, ByVal lpFileSystemNameBuffer As String,
       ByVal nFileSystemNameSize As Long)

En un formulario :

dim Vol as string*256, FileSystem as string*256, unidad as string
dim longitud as long, NumSerie as long, Flags as long

unidad = "c:\"
Call GetVolumeInformation(unidad, Vol, 256, NumSerie, longitud, Flags, FileSystem, 256)

debug.print "Etiqueta : " + left$(Vol,instr(vol,chr$(0)))
debug.print "Nº de serie : " & NumSerie
debug.print "Sistema de archivos : " + left$(FyleSistem,instr(FileSystem,chr$(0)))