The Zune requires the Zune software (Windows only) to sync and only the Zune software is able to sync a Zune. There are hacks to be able to use third party software to sync a Zune but those hacks rely on old Zune firmware and previous versions of the Zune software. I don't believe there are hacks for the current Zune firmware and software.
You can download and install the
Zune software if you want to get an idea for what the Zune experience would be like. I tried it recently. I found it to be the kind of software that would be good for a 14 year old but horrible for an adult or power user.
You could probably sync a Zune using techniques similar to how people use MC to sync with an iPod Touch or Phone. Create a directory to serve as your faux Zune and have MC treat that directory as a portable device. Have MC sync to that directory. Then have the Zune software treat that directory as your entire music library and sync it. But what a kludge and likely to have unforeseen problems especially syncing 100GB.
An iPod Classic is a better choice. MC supports the iPod Classic.
I'd love to like the Zune. It's wonderful hardware. Does gapless playback. Great sound quality. It's all good except being locked down to only using the Zune software.
The iPod Classic is good hardware. Does gapless playback. Has reasonable sound quality (not as good as the Zune or previous iPod versions). Third party tools available are able to sync but not supported by Apple. Don't even think about third party support for the Touch or iPhone.
It's not a good situation to have two of the best portable players locked down to only using their own software. And the future direction of Apple with the Touch and iPhone being completely locked down is not good. I also see the Touch as the future of the full size iPod and the Classic style going away.
I use an iPod Classic 80GB. I'm not overly proud of having bought into the Apple model of locked down hardware. But what can I do? I absolutely require gapless playback and that really really really limits my choices.
(A secret nightmare of mine is getting hired by Microsoft and having to smuggle my iPod into work or suffer through using a Zune)