Maybe you'd better look at Adobe Presenter if you need only to convert a PPT to an eLearning course?
Captivate is much more powerful, but its principal goal is not to convert PPT's. Each PPT-slide is converted into a movie slide so that all animations will be transferred properly. Personally I never create presentations in PPT but always directly in CP. You could import only the backgrounds, and create the other objects in CP. Images can be imported into the library, audio as well.
Lilybiri