From: http://blogs.msdn.com/virtual_pc_guy/archive/2006/09/21/760371.aspx
Option Explicit
Dim strComputer, objWMIService, colVMs, vm, totalDisk
totalDisk = 0
strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\vm\virtualserver")
Set colVMs = objWMIService.ExecQuery("SELECT * FROM VirtualMachine",,48)
For Each vm in colVMs
Wscript.Echo "-----------------------------------"
Wscript.Echo vm.name & ":: Disk space used: " & _
vm.DiskSpaceUsed / 1048576 & _
" MB (" & vm.DiskSpaceUsed & " bytes)"
totalDisk = totalDisk + vm.DiskSpaceUsed
Next
Wscript.Echo "-----------------------------------"
Wscript.Echo "All virtual machines"
Wscript.Echo "-----------------------------------"
Wscript.Echo "Disk space used: " & totalDisk / 1048576 _
& " MB (" & totalDisk & " bytes)"
The nice thing is that it gives you the total disk usage, even when the virtual machine
Be sure to read his entire "Developing on Virtual Server" blog
http://blogs.msdn.com/virtual_pc_guy/archive/tags/Developing+on+Virtual+Server/default.aspx