Dim FSO, File, OldName, Testing, Folder
Set FSO = CreateObject("Scripting.FileSystemObject")
Set Folder = FSO.GetFolder(".")
Set Testing = New RegExp

For Each File in Folder.Files
OldName = File.Name
Testing.Pattern = "[A-Z]"
If Testing.Test(OldName) = True Then
File.Name = Lcase(OldName) & ".bak"
File.Name = Lcase(OldName)
End If
Next

Wscript.Echo "Renaming Complete"
Wscript.Quit