I will look at DLT. I haven't looked at it yet because my impression is that it's extremely expensive. I will keep it in mind though.

It used to be. But now SuperDLT is out and the older DLT technology (which is lower capacity but still rock-solid reliable) has come down in price. Not sure if it's come down enough for you or not. But think about how much time you've been spending fucking around with problems with the DAT tapes and add it all up. How much money is that time worth to you? Now imagine sticking a tape in every night and forgetting about it. That's DLT.

Can you suggest any backup software for a (very) small business? All we need to do is schedule a backup to be run everyday and pop the media out of the drive when done.

If you don't want to spend any money, then there's backup software built-in to most versions of Windows which will do it for you. And keep in mind that most of the time when you buy a backup drive, it will come with software.

Personally, I swear by ArcServe, but it's so feature-heavy that even setting up a simple "stick one tape in each night" backup system is a bit of a learning curve. It might be overkill for what you're looking for. Then again, you're a pretty tech-savvy guy so I don't think ArcServe would be daunting to you at all, and you'd eventually grow into its more powerful features.

Hmm. I think some of the DLT drives are sold with ArcServe included....