The best and the easiest way to do what you are after is to burn the playlist to a disk through itunes itself, and the others should be able to play the disk without issue anywhere at all.
When Itunes burns the .m4p's to the disk it loses the drm and is playable where ever you are able to play disks normally.
none of the other methods/ convertors as suggested in this thread are likely to work, accept for playing the audio and having it recorded through whatever recording software, but if your machine has a dvd/cd drive burning is the easiest quickest way to do what you are after, imo.
“The most important thing in life is not the triumph but the struggle. The essential thing is not to have conquered but to have fought well.”