Cut and paste of my reply on the General Board.
Darksabers OPT Station. http://www.darksaber.freeserve.co.uk/
Many OPTs come with *.shp files as well though so you may want to get MXvTED there as well as this is a more automated process.
Darksaber also has full tutorials on the use of these utilities and some truly excellent OPTs.