If you have iTunes, you already have an mp3 player. What do the icons of the mp3 files look like? Do they look like QuickTime, iTues, or generic white file icons?

Try this: open iTunes. Drag the files you want to hear to the open library window. What happens? If the titles show up, you can play them in iTunes.

On rare occasions, there are mp3 files that iTunes cannot play. Other players such as Audion or SoundJam (if you can find it) sometimes can play them. If not, download another version of the same file.

With earlier versions of LW, I was never able to launch anything but a movie preview which then froze my computer. But that was a long time ago. If you are on an older, slower Mac, however, this might be the problem. There are just not enough computer resources to run Java-bloated LW and an audio program at the same time.