how about u play it in realplayer and set recording to line out, then record that in sound recorder or something similar, then it shodnt be too hard to convert the wave file to mp3.
You could use a program called Total Recorder that will record any type of audio playing through your sound card whether it is from software or line-input. Total Recorder program records to .wav files so you would need to convert to .mp3
You could also try Super Mp3 Recorder that records any audio playing through software directly to .mp3 files.