Hey, jvhuiz, the full list of formats that the Reader supports can be found
here -- but the short answer is no it doesn't support PRC or Mobi files. There are a number of ways to convert them, but the shortest answer there is probably
Calibre.
Have a look at the wiki entry, and do a quick search in the forum and you'll find lots and lots of info on using it.
Plus, I'm sure there will be many folks eager to share more answers to your question.