DOS_SPX.EXE and DOS_AGNT.EXE are agent TSRs.  To 
  back up or restore a Windows workstation, these TSRs 
  MUST be loaded BEFORE loading Windows.  Also, your 
  AUTOEXEC.BAT file should load them AFTER IPX.COM 
  and NETX.COM.
  If you click YES, Setup will APPEND these lines to the
  AUTOEXEC.BAT file.