can not install rtems4.8-tools-autotools-17.exe

[阎淼]

hi,
  I am installing rtems development enviroment on windowsXP.
  I followed the wiki page, installed mingw, MSYS-1.0.10.exe and
msysDTK-1.0.0.exe into their default directory.
  but when I install the rtems4.8-tools-17.exe, a message box comes up saying

  "MinGW not installed. Please install MinGW from www.mingw.org"?

   is there something wrong with my process?