Alice, given the choice, I would opt for the smaller Mp3 format (I am missing an Mp3 converter at the moment) but either are fine. I think where Real really scores is with the streaming which can be used to create a live broadcast or to allow a file to play without having to wait for a whole file to download but you need some kit to be able to do that.

I have successfully managed to use my PC as a Real Server to "broadcast" a CD but with a 56K modem, its limit is one user and with an IP address that is allocated dynamically (changes each time I connect) and no means of DNS resolution (mapping a URL to an IP address), it is not practical.

Jon