iamlost - 11:59 pm on Feb 14, 2007 (gmt 0)

The title attribute will normally override the alt in IE.

If only the alt is used IE will display its contents as a tooltip.
<img src="foo.jpg" alt="foo"> : tooltip=[foo]

If title is used, even empty, IE will show it instead.
<img src="foo.jpg" alt="foo" title="pic of a foo"> : tooltip=[pic of a foo]
<img src="foo.jpg" alt="foo" title=""> : no tooltip.