Ah, that clarifies things quite a bit.
For your calendar information, I'd lean towards the "cal" extension. That may already be installed for you if you just got started. If not, it's a great thing for scheduling and is easy to use and view. Please read the manual if you need to install it to ensure that you create the folders appropriately. I created them using my best guess at the time and really wish I'd done that differently now. :P
If this is just for Sporting-type purposes, there are extensions specifically designed for sports. They organize teams, rosters, schedules, record history of the games, etc. I think one is called "sportsclub", but just don't remember off the top of my head. I played with it briefly and didn't have time to go further.
Powerpoint - that one's a little out of my league, but I'm relatively sure that there are extensions to view PowerPoint as a slideshow. Worst case scenario would be to export the slides as graphics files and display them as a slideshow that way. If you want all of the cool animations and such, you're probably going to need a 3rd party app to do the conversion. I know there are programs to convert the slideshow to a video, but don't use them often.
One great place just to view the extensions is in the www.typo3.org repository section - you can search for extensions and read a little more about them.
Have fun getting started!
-Peter Schott