My cassette of the week is the Rough Guide of the Music of Portugal from the World Music Network at "
http://www.worldmusic.net/" . It is a compilation cassette which gives a tiny taster of the work of twenty Portuguese artists.
I am not saying that it is the best work of any of these but it is an excellent way to hear a large selection of music and musical styles and decide your preferences for yourself.
At the website, you have a chance to listen to a track from sixty of their world music series. The choice from the Portuguese album is one of my favourite tracks, Jose Afonso and Saudades de Coimbra.
There is also a Brazilian album.
Give it a try. Sing along. Remember learning is fun.