HOW TO CONVERT SONGS WITH .DCF FILE EXTENSION TO .MP3 PROVIDED WITH NOKIA 5800 XM (PLEASE READ DETAIL BELOW)?

Firstly get an audio conversion program from the internet. You can search for the top 10 and then download the first one. Then convert those files into mp3 or whatever you want to convert to and then windows media player should be able to play those files with ease. Just make sure the program supports your type of file extension (.mp3) etc.