CSS rollovers do not work in IE6 because IE 6 does not support the “:hover” pseudo class on any element EXCEPT anchors (<a >)
There is a simple fix for this however, Dean Edwards has comprised a javascript library which is hosted on Google Code that you can “hotlink” directly from google (legally) in the form of a conditional statement and it will make IE 6 play nicely. In other words, everything that IE 7 supports, this script will make IE 6 support as well.
Here is what you would need to place in the <head> of your page…
<!--[if lt IE 7]>
<script src="http://ie7-js.googlecode.com/svn/version/2.0(beta3)/IE7.js" type="text/javascript"></script>
<![endif]-->
Good luck!
