I built a 5.3 binary distribution for Cygwin (thanks to much assistance from Glynn). It is at:
http://www.greenwoodmap.com/grass/grass5.3
It includes Glynn's working NVIZ. See config.txt for information on other options.
Regarding "d.mon png" I added gd to 5.0.3 but it still did not work. I also tried it under 5.3 (which supposedly does not require gd) and it did not work there either.
Also tried adding fftw as recommended at:
http://freegis.org/cgi-bin/viewcvs.cgi/*checkout*/grass/documents/release_rules.txt
But failed to get it working either.
--
Richard Greenwood
www.greenwoodmap.com