At the moment only source code is available for download. I'm planning to add binary releases in the future.
You can get the source code for NPGPX from the SourceForge mirror servers. The links below will take you to SourceForge's download system where you can choose the mirror that is closest to you - they are not direct links to the source code packages, so don't use the Save link function in your browser. Also, the source code packages are compressed using the bzip2 format, so you will need a program that can unpack these files.
If you want the latest development version of the code, which may have new features but may also be incomplete and buggy, you can get it from the CVS repository. For this you need a CVS client, like this one. The commands you should use to get the source code from CVS are these:
cvs -d:pserver:email@example.com:/cvsroot/npgpx login cvs -z3 -d:pserver:firstname.lastname@example.org:/cvsroot/npgpx co npgpx
When you are asked for a password, just hit enter.
Building NPGPX from source code is not completely straightforward, see the README file for details.