[mMark]

I've had the same problem with a couple government websites up here in Canada (don't ask why our Canadian Gov websites aren't compatible yet... incredibly frustrating).

Installed a fully secured suite of FF in a law office w/IETabs. Forms wouldn't load in it. Chaos ensued.

None of them ever used FF again and now tell everyone it's "that crappy program tech support installed".

Now I didn't uninstall IE but I hid the icon. Lesson learned. Just leave the icon in their quicklaunch with FF on the left of it. Instruct them to use the orange icon because it's safer and faster. If they don't use it and their computer gets fubar'd you can just tell them that you told them so and fix it up for them.

[windsurfer]

I worked for Public Works and Services Canada, and all our sites must be compatble with IE 6 and Firefox 3.0 before they are pushed to production.