I have written some detailed notes about installing Moodle on an ordinary Mac using the ordinary OS X client version 10.3--not server version. The server version is expensive and not recommended unless you are running a Mac-equipped classroom laboratory. The notes are on this Moodle site at...
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This is a wiki document, so I would invite all Mac server users to add their comments or corrections.
Other than these tips and warnings, I think Mac OS X is the easiest and most fun way to host
Moodle of all operating systems