iTunes delivers their audio in a file format called AAC. This plays on an iPod or in the iTunes player on your computer. This file also plays in most MP3 players these days. Bear in mind you can use iTunes to burn and create a CD for playback through conventional streos. It is a very user friendly format. If you find the AAC file does not play in your MP3 player, you can use iTunes to convert the AAC file to an MP3.

I'll buy it Friday morning from a retailer.
However, I think I'll buy the Gordian version of "Beneath A Phrygian Sky" on iTunes. I have a question: I don't know how it works... I downloaded the installing software and I installed the program, I can find Loreena and her album but the question is: what format is the downloaded track? Can it be played only on an iPod or can I listen to it in a normal and cheap mp3 reader?
Thanks to everyone who wishes to help.