It's 2013 and I want to convert AIFF audio files to MP3s

Question

It’s 2013 and I want to convert .AIFF audio files to .MP3 files on my Mac.
I created some sound files as .MOVs for a band’s website but that format doesn’t work for some Windows OS users who refuse to fetch a QuickTime plugin for their Explorer or Firefox internet browser…("don’t make them think; it either works or it doesn’t.")
I have been told that MP3 audio files are still the most common audio files on the web and I want the band’s music to be in the most-accessible format.
Thanks,
Ron
Also, this is my first Apple Support question and I would appreciate being pointed to the most appropriate forum(s).

Answer 1

Thanks, Joe, that was very useful!
For other people with my problem I should add some of the missing puzzle pieces —
1) A while ago I loaded the songs from the band’s CD onto a previous, now dead, Mac laptop (with a previous Mac OS) and used QuickTime 7 to create down-sampled (and smaller) .mov files. Then I deleted the original .aif files from that computer.
2) Now (back to the present) I wanted the .aif audio files on my new computer to convert them, but the computer doesn’t have a CD/DVD drive. My solution was to use my partner’s iMac.
3) I inserted the CD into the iMac’s drive, clicked "no" to iTunes’ dialog asking if I wanted to import them, created a folder on the desktop, then opened the CD folder on the desktop and copied the songs into the newly-created folder.
4) I copied the new .aif files to a thumbdrive then deleted the .aifs from the iMac.
5) I put the copied thumbdrive .aif songs onto my MacBook Pro Retina (where I had changed iTunes Preferences to MP3) then I 'dropped' the sound file icons onto the iTunes icon in the dock.
5) In iTunes I right-clicked on the songs and chose "Create MP3 Version".
6) Next, I right-clicked on the MP3s in iTunes and chose "Show in Finder". This opened another folder (~/Music/iTunes/iTunes Media/Music/Unknown Artist/Unknown Album/), revealing the MP3s.
7) I created duplicates of the MP3s and moved them to my band's media folder (and will put them on the website after renaming them and editing their webpage for the new audio filenames).
8) Finally, I will delete the .aif and .mp3 songs from my iTunes, using iTunes' interface to ensure it doesn’t get confused.
Sheesh. but I’m still happy to not have a CD/DVD drive on my MacBook Pro. I very rarely use CDs and a drive on the laptop would add bulk and weight while being mostly useless.