>>I think this is the best approach. Don't make the decision for the user, but allow them to decide for themselves.
>
>Just as long as you make a good guess for the default. Many users are scared stiff of Options. Cooper insists that computers do more to make the right choice for the user, instead of asking them about every detail, or, worse yet, hunt through a menu hierarchy looking for a dialog box to make it work right in the first place.

I think I would default it to on, but present the user with the option of turning it off on the spot. Similar to how [ahem] Microsoft includes a "Do not ask me again" checkbox in their dialogs. This enables them to turn it off right then and there. I would also include it in the options dialog to allow them to turn it back on if they wanted to.