Fallback for IE7 or lessBrowser Info Environment
What you need to do is create a pair of complementary conditional comments, effectively an if-else structure, within the view.php of a tab template.
Its a good practice to never modify a template in place, but to copy/edit it to:
Containing view.php and view.css (if there is one). It is only view.php that the above conditional comments are added to.
You will need to apply this template to ALL Magic Tabs blocks in the set, not just the first Magic Tabs block as you could with other templates.
I use it on all my sites. This alerts users about IE6 and less, (but not IE7 by default).
The home page uses Magic Tabs and many of my addons are used through the site.