Another dropping menu

I’m having a problem with my menu dropping to bottom of content section. This happens when I “float: left;” the lefthand menu in a 3-col format. When I use “position: absolute; for the menu, it works in Firefox but not in IE. Here’s the CSS for my BODY & PAGE LAYOUT:

body {
font-size: 14px;
line-height: 18px;
font-family: Verdana, Georgia, “Times New Roman”, Times, serif;
margin: 20px;
}

#rap {
background: #fff url(‘bg1.gif’) repeat-y left;
margin: 0px 200px 0px 0px;
border-bottom: 0;
text-align: left; /* IE 5.5 hack part II */
}

#masthead {
background: #90a090;
border-bottom: double 3px #aba;
font: italic normal 100% ‘Times New Roman’, Times, serif;
letter-spacing: 0.2em;
margin: 0;
padding: 15px 10px 15px 60px;
border-bottom: 1px solid #565;
}

#main {
backgound: #fff;
margin-left: 225px;
top: 155px;
width: 280px;
border: 1px solid #000;
height: 100%;
}

#content {
float: left;
width: 280px;
}

#menu {
background: #fff;
float: left;
left: 20px;
border: 1px solid #000;
width: 125px;
}

#rmenu {
background: #fff;
position: absolute;
right: 250px;
top: 135px;
border: 1px solid #000;
width: 185px;
}

.clearer {
clear: both;
height: 0;
margin: 0;
padding: 0;
}

#footer {
margin-bottom: 0;

THANKS IN ADVANCE