The help from
http://sourceforge.net/projects/gimp-win/files/ should work but you should enter in Gimp /edit preference and set in Help the option "web browser to use" web browser..because the default can't work since in the windows version there is no any gimp brower to use
And for gap Gap 2.6 it works, is quite old but still there are not new stable version but may be difficult find the download link, for the 32bit i was hosting GAP 2.6 on http:/photocomix_resources.deviantart.com/gallery
A more recent version 2.7 (not officially a stable version but seems working well , even if display a load of flashing black windows when loading is here ) at 32bit is
http://sourceforge.net/projects/gimp-packagers/files/GAP-2.7-32bit-Win.7z/downloadLast for 64bit you may found GAP.26 at
http://samjcreations.blogspot.it/instead the version of Gap that you may found at
http://sourceforge.net/projects/gimp-win/files/ is from 2005 and can't work with modern gimp