These were downloaded from http://ngrep.sourceforge.net
The linux-elf-static binary should run on any linux system. It's a good fallback if your Linux distribution does not already come with it, but because it comes bundled with all the libraries it needs, it will take more disk space and memory when it runs.
The win32-bin package holds "ngrep.exe"; extract it with winzip and place it somewhere in your path (perhaps c:\windows).
ngrep.8.html is a copy of the manual page for ngrep, including a summary of all the command line options.
The .tar.bz2 file holds the source code for the tool if you need to compile it from source. We did not include the windows source, but that's available from the Ngrep home page.
There's a quick introductory article on ngrep at ../doc/ngrep-intro.v0.8.html .