Any ideas why I can't add two audio files to the Project Media or even drag and drop them to the timline? I can play them in other audio programs like WMP and itunes. One is an .ogg file and the other is mp3.

MP3 should be fine. ogg don't know. Mp3 file might be corrupted. Convert them with another program first. If they are not being accepted then the problem "probably" lies with the files, not Vegas in this case.