Hi strutsam, Welcome to SitePoint!
From here on out always be sure to start your own thread when you need help with something. It takes the OP's thread off topic when we try to give fixes to two different pages.
For now though it looks like I can give you a quick fix for your page. It is a z-index bug in IE6/7. The problem is that you have set you have set your z-index in the wrong place with your nav. You set it on the sub UL when it really belongs on the parent div #category. Let's go ahead and trip "haslayout" for IE7 also.
<font color='Blue'>min-height:0;</font> <font color='DarkGreen'>/*IE7 haslayout*/</font>