This is where I usually get free reggae music - all songs can be downloaded for free, legally and it has great diversity. Also all mp3s are universally compatible. Enjoy ;)
You have to pay for it nowadays cause of the law. However, my friend used to go on a website called kazaa but rememer it is illegal and if you get caught your looking at a hefty fine so your going to have to ask yourself is it really worth it?
Don't forget the vast amount of Reggae bands on Myspace. Use this search to find bands relating to reggae. Most artists pages will have a download option for 4 songs.