I did it for fun and revenge and it turned out to be the
best idea ever.
I don't care about them.
They don't care about cluttered layout.
Maybe they will visit my website with
a proper browser and notice
the difference and switch. It's perfect.
<? if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE') !== false): ?>
<!-- Insert your ad code in here -->
<? endif; ?>