If you have MSCOMDLG32.OCX, and registered it you can use the following code:
 Code:
Function BrowseForFile($strPath, $strFilter)
  Dim $objDialog, $intResult
  $objDialog = CreateObject("MSComDlg.CommonDialog")
  $objDialog.Filter = $strFilter
  $objDialog.InitDir = $strPath
  $objDialog.MaxFileSize = 256
  $objDialog.Flags = &80000+&4+&8
  $intResult = $objDialog.ShowOpen()
  $BrowseForFile = $objDialog.FileName
EndFunction

$FileName = BrowseForFile("c:","*.kix")