I have just been using Explorer in Windows XP- in XP, Windows has the built in ability to open zip files, and delete and copy stuff into and out of it.
I also tried using WinRar on Store...didn't work.
All the other music would play, but the ones I put in didn't. I suspect it has to do with the format- iTunes reports that fed_01_main.mp3 is an MPEG-1, Layer 3, 128kbps, 44.100 kHz audio file.
The music file I'm trying to put in is a MPEG-2, Layer 3, 64kbps, 22.050 kHz audio file.
No clue how to change that.