To convert an Amigaguide formatted document into HTML, you can use my program AmigaguideToHTML.
If you just want to view an Amigaguide formatted document on Windows, and don’t need to convert it, you can use Steven Eckles’ WinGuide 4.0 program (172 kilobytes). The program is shareware, but is not restricted in any way; however, it doesn’t support a number of Amigaguide commands (including some from the original Amigaguide), and Steven Eckles is no longer working on the program.