If you aren't going to run a mic tower... then do what i do... I have a sony minidisc player as well and use it to record live shows. I use a Sony ECM-717 microphone and run the cable up my shirt and either put clip it to my collar (it has a clip) or if you wear a hat, you can clip it to that as well without looking too obtrusive. Be close to the stage, but if you can't get a decent spot near the speakers, then try to center yourself...
And FLAC or SHN (shorten) formats are much better than mp3's. Check out etree.org for more information on those formats... you may find some nice live shows to download from their ftp servers as well.