I am trying to automaticly open an office doc (word/excel/ppt/...) from sharepoint while using Firefox browser in the browser. I manage to so manually (do manually what my method (written in C#) soppose to do) - so i figure that all the settings [the feature "Open Documents in Client Applications by Default" is DEACTIVATE ] in the sharepoint are ok - I can open the doc in the browser just by clicking on it.
Open Documents in Client Applications by Default - settings just works for files that can be rendered in the browser like (swf,txt). However opening MS Office based through SharePoint is a different thing.
For Excel to open in your browser through SharePoint document libraries you must enable Excel Service Applications at the farm level.
For rendering word and powerpoint files you need Office Web Apps integrated with SharePoint 2010.
I am not really sure, but Firefox do have some limitations rendering office documents which you get in technet reference for known browser limitations for SharePoint 2010. But unless you have Office Web Apps you cannot open a powerpoint file through sharepoint.