.MSG files are Microsoft Outlook, right?
My understanding is that they should be human readable using a legitimate text editor. I would recommend downloading a legitimate text editor such as
TextWrangler and putting it in your Applications folder.
Make copies of the files (i.e. onto your local hard disk; you want the copies on the flash drive untouched in case I'm wrong) and control-click one of the files. Select Open With... and choose TextWrangler if it appears. Otherwise, select Other... and select TextWrangler.