I believe 10.5.8 is Leopard. The calibre download site says
Quote:
Note- If you are using OS X Tiger or a PowerPC Mac, the last version of calibre that will work on your machine is 0.7.28, available here .
- The app cannot be run from within the dmg. You must drag it to a folder on your filesystem (The Desktop, Applications, wherever).
- To install the command line tools, go to Preferences->Advanced->Miscellaneous
- In order for localization of the user interface in your language, select your language in the preferences (by pressing ⌘+P) and select your language.
|
so as long as you are on an Intel based Mac you should be fine.