I see what you mean, OP. I'll let this site explain to you how since it's convenient.
Converting iTunes to MP3
askbobrankin.com
If you right-click on a music track in iTunes, there is an option to Convert Selection to some other format.
Probably it says "Convert Selection to AAC", which is useless because your iTunes tracks are already in AAC format!
You'll need to change your import settings to get iTunes to import the track as MP3. In iTunes 8, go to Edit / Preferences / General and click the Import Settings button. In older versions of iTunes, click on Edit / Preferences / Importing (or Edit / Preferences / Advanced / Importing). Your goal is to change the Import Using from the default setting to "MP3 Encoder".
http://askbobrankin.com/aac-mp3-1.jpg
Click OK to save this setting.
Now when you right-click on a music track, there is an option to Convert Selection to MP3. But just try it... iTunes will tell you that "Protected files cannot be converted to other formats."
http://askbobrankin.com/aac-mp3-2.jpg
Now here's the problem. After he says that if a file is protected, there is not that many options you could do. If you're lucky enough to Google up yourself something that makes mp3 files unprotected, then you can do that. There are alternatives so I suggest you can try and read up more on here:
http://askbobrankin.com/convert_itunes_to_mp3_format.html
How can you tell what format that current file is playing in? You need to find the song that you are looking for OUTSIDE of iTunes, right click the file and go to properties.
(Example: Your music could be on the desktop, or your 'My Music' folder, or the directory where iTunes is stored under All Programs by default).
