I've been using Notmad Explorer as well as Creative's Explorer, but I don't think it's the client software at fault; I think it's the firmware. In fact, one of the reasons I tried upgrading in the first place was because of the promise of driver-free integration with Windows Explorer so I could use it as a removable drive -- which does work, for small values of "work".

On the other hand, the Zen is >4 years old, and I won it in a raffle anyway, so I think I've had the use out of it. Just a handy excuse for getting an iPod, really...