Try mplayer first. Before you install from yumex, you have to make sure you have ALL of the repos files from the top fo this thread, otherwise you may miss some dependencies.
http://www.ps3hax.com/yellow_dog_lin...tml;msg332#new
Then you can TRY it with yumex and report back. Look in the How To Install Mplayer thread because you will still have to configure the subfont as instructed. report back.
Yes, you can play .wmv files with either player. Open Office Presentation can display powerpoint. Go 4 it.