I'd suggest the first one,
"Creative Zen Micro Firmware 1.11.01".
The other firmware looks like it only adds
MS DRM, requires more memory, and adds no real benefits.
MS DRM would likely disable listening to many digital music files
that aren't strictly identifiable, as to its' original source.
Also, do a Google search for "Zen Micro Firmware", there's probably
some discussion forum concerning the benefits of the two firmwares.