You can incorporate some of the code from one of these sites:

Jim Rech has a BrowseForFolder routine at:
http://www.oaltd.co.uk/MVP/Default.htm
(look for BrowseForFolder)

John Walkenbach has one at:
http://j-walk.com/ss/excel/tips/tip29.htm

Your main routine will be:

Option Explicit
Sub testme01()
 
   Dim myNames() As String
   Dim fCtr As Long
   Dim myFile As String
   Dim myOldPath As String
   Dim myNewPath As String
   Dim MstrFileName As String
   Dim TempWkbk As Workbook
       
   'change to point at the old folder
   myOldPath = GetDirectory("Select OLD Folder")
   If myOldPath = "" Then Exit Sub
   If Right(myOldPath, 1) <> "\" Then
       myOldPath = myOldPath & "\"
   End If
   
   'change to point at the new folder
   myNewPath = GetDirectory("Select NEW Folder")
   If myNewPath = "" Then Exit Sub
   If Right(myNewPath, 1) <> "\" Then
       myNewPath = myNewPath & "\"
   End If
   
   MstrFileName = "mstr.xls"
   
   myFile = ""
   On Error Resume Next
   myFile = Dir(myOldPath & "*.xls")
   On Error GoTo 0
   If myFile = "" Then
       MsgBox "no files found"
       Exit Sub
   End If
   
   Application.ScreenUpdating = False
   
   'get the list of files
   fCtr = 0
   Do While myFile <> ""
       fCtr = fCtr + 1
       ReDim Preserve myNames(1 To fCtr)
       myNames(fCtr) = myFile
       myFile = Dir()
   Loop
   
   If fCtr > 0 Then
       For fCtr = LBound(myNames) To UBound(myNames)
           If LCase(myNames(fCtr)) = LCase(MstrFileName) Then
               'do nothing, skip the master file
           Else
               Application.StatusBar _
                      = "Processing: " & myNames(fCtr) & " at: " & Now
                     
               Set TempWkbk = Workbooks.Open(Filename:=myOldPath _
                                  & myNames(fCtr), ReadOnly:=True)
                               
               TempWkbk.SaveAs Filename:=myNewPath & myNames(fCtr)
               TempWkbk.Close savechanges:=False
           End If
       Next fCtr
   End If
   
   With Application
       .ScreenUpdating = True
       .StatusBar = False
   End With
 
End Sub

But in a different module, put all this code (From John Walkenbach's site):

Option Explicit
Public Type BROWSEINFO
   hOwner As Long
   pidlRoot As Long
   pszDisplayName As String
   lpszTitle As String
   ulFlags As Long
   lpfn As Long
   lParam As Long
   iImage As Long
End Type

'32-bit API declarations
Declare Function SHGetPathFromIDList Lib "shell32.dll" _
 Alias "SHGetPathFromIDListA" (ByVal pidl As Long, ByVal pszPath As String) _
 As Long

Declare Function SHBrowseForFolder Lib "shell32.dll" _
   Alias "SHBrowseForFolderA" (lpBrowseInfo As BROWSEINFO) As Long

Function GetDirectory(Optional Msg) As String
   Dim bInfo As BROWSEINFO
   Dim path As String
   Dim r As Long, x As Long, pos As Integer

'   Root folder = Desktop
   bInfo.pidlRoot = 0&

'   Title in the dialog
   If IsMissing(Msg) Then
       bInfo.lpszTitle = "Select a folder."
   Else
       bInfo.lpszTitle = Msg
   End If
   
'   Type of directory to return
   bInfo.ulFlags = &H1

'   Display the dialog
   x = SHBrowseForFolder(bInfo)
   
'   Parse the result
   path = Space$(512)
   r = SHGetPathFromIDList(ByVal x, ByVal path)
   If r Then
       pos = InStr(path, Chr$(0))
       GetDirectory = Left(path, pos - 1)
   Else
       GetDirectory = ""
   End If
End Function