Option Explicit
Dim StrIO As String
Sub BulkCopier()
Application.ScreenUpdating = False
Dim strInFolder As String, strOutFolder As String
Dim strInFile As String, strOutFile As String
Dim StrPrefix As String
StrIO = "Choose an INPUT folder"
strInFolder = GetFolder
If strInFolder = "" Then Exit Sub
StrIO = "Choose an OUTPUT folder"
strOutFolder = GetFolder
If strOutFolder = "" Then Exit Sub
StrPrefix = "\" & Split(strInFolder, "\")(UBound(Split(strInFolder, "\"))) & "_"
strInFile = Dir(strInFolder & "\*.doc", vbNormal)
While strInFile <> ""
  On Error Resume Next
  FileCopy strInFolder & "\" & strInFile, strOutFolder & StrPrefix & strInFile
  strInFile = Dir()
Wend
Application.ScreenUpdating = True
End Sub
 
Function GetFolder() As String
Dim oFolder As Object
GetFolder = ""
Set oFolder = CreateObject("Shell.Application").BrowseForFolder(0, StrIO, 0)
If (Not oFolder Is Nothing) Then GetFolder = oFolder.Items.Item.Path
Set oFolder = Nothing
End Function