Hey guys, I havent read at many places about this, so I thought I'd share. It may be a little neat thing for you to do in your spare time if you're one of those kinds of people who just has to uncover every little thing in Megaman games.
After you beat all of the Mavericks, before you go to the Jakob level, go back to Noah's park. You'll be able to fight Vile in a more powered up version. I think this is only for normal/hard difficulty though.