I got nothing against mygallery or the other gallery mod but the easiest one to use and install is Gallery over at http://gallery.menalto.com

it is the easiest one to install and will work with php-nuke 'out-of-the-box'.

just follow the instructions for using it with php-nuke, which amounts to uploading it as a module into oyur modules directory. I found the instructions rather explicit and after the upload of files it took me less than 3 minutes to create the two extra folders required and do a little chmod'ing beofre then after the setup, which is done simply by following the link to the module on your menu block.

All these other gallery scripts for php-nuke just take too much manual editing of files. Atleast for my tastes they take too much work to get running.