I've tested both on IEtester. It should work. To do a simple test try
<title>...meeting rooms -</title>
<meta http-equiv="content-type" content="text/html;charset=UTF-8" />
<link href="css/main.css" rel="stylesheet" type="text/css" />
<!--[if lte IE 6]>
<link rel="stylesheet" type="text/css" href="css/mainiesix.css" />
<style>
body {
background:#000;
font-size:40px
}
</style>
<![endif]-->
<!--[if IE 7]>
<link rel="stylesheet" type="text/css" href="css/mainieseven.css" />
<style>
body {
background:red;
font-size:40px
}
</style>
<![endif]-->
Test in ie6, bg will be black, in ie7 bg will be red and in ff, it will display as default