Hi,

what is your goal?
Just backup these files (wma in this case) onto a disc or do you want to make an audio CD from them?
In the first case, just burn a data CD.
In the second case, you need 2 blank discs. Add as many files to the audio CD project as you like (until the disc is full) and create a second audio CD project for the rest of the files.

Converting wma to mp3 is not a good idea, quality wise. In case you want a mp3 disc for your car stereo etc., it is better to rip them again from CD - but this time in mp3 format. Windows Media Player is not recommended for that job. I prefer CDex for this.

Michael