Or use Fso, works the same as Dir just imo it's faster.

 Code:
Dim $FSO, $Path
$FSO = CreateObject("Scripting.FileSystemObject")
$Path = $FSO.GetFolder("C:\")

FindFiles($Path, "boot.ini")

Function FindFiles($Root, $sfile)
  Dim $SubFolder, $file
  For Each $file In $Root.Files
    If $file.name = $sfile
      ? $file.path
    Endif
  Next
  For Each $SubFolder In $Root.SubFolders
    FindFiles($SubFolder, $sfile, $dest)
  Next
EndFunction