Firstly, how the hell did he get DRM protected wma files on a cd-r. I thought you couldn't do that.
I had the same problem with HMV Digital downloaded music. I used FairUse4WM, which found the keys of the copyright and removed them from the wma files. However, seeing as you didn't download the said files on your pc, it probably won't find the keys anyway. You could try, though: click here
There is also a program called SoundTaxi - it costs around £8, but it is worth paying for.
Then again, you could always use Total Recorder 6.0 to record the music - play the song in media player and it will record it for you in 192kbps (or higher) mp3. However, this is not the fastest solution, as it means playing the songs all the way through.
Hope this helped