On Linux, it doesn't really matter where you install NRPE or the plugins. Use the init-script provided, and edit it the lines pointing to the path where nrpe.cfg file and the nrpe daemon to match where you've placed them on your system. You'll also need to edit the appropriate lines in nrpe.cfg to get the correct paths to your plugins.
The vast majority of the systems I've monitoring are *nix machines, and there are only a few Windows machines, so I'm not as familiar with using NRPE on them. I know that you'll still need to edit nrpe.cfg to point to your plugins. As far as where to place that file in relation to the actual daemon...well, I just place everything in one folder and it seems to work fine, as unorganized as that may seem.
You'd probably want to place the NRPE daemon and the config file in the same folder. It won't matter where the plugings are, as you can edit nrpe.cfg to point to them.
Edited Thu Feb 02 2006, 10:13PM ]