The only thing itunes does to 'em is keep 'em in their own special protected format. They're independent files, kept in whichever dir is set as your music folder (look under edit->preferences->advanced for the 'media folder') and you can do with them as you please.

It is possible to convert them, for a minor fee, to 'unprotected' files, which you can then turn into mp3s right there in iTunes by right-clicking and saying 'make mp3 version'.

That help? ^^