Целевые ВСЕ версии IE:
<!--[if IE]>
<link rel="stylesheet" type="text/css" href="all-ie-only.css" />
<![endif]-->
Целевые все, кроме IE
<!--[if !IE]><!-->
<link rel="stylesheet" type="text/css" href="not-ie.css" />
<!--<![endif]-->
Целевые IE 7 ТОЛЬКО
<!--[if IE 7]>
<link rel="stylesheet" type="text/css" href="ie7.css">
<![endif]-->
Целевые IE 6 ТОЛЬКО
<!--[if IE 6]>
<link rel="stylesheet" type="text/css" href="ie6.css" />
<![endif]-->
Target IE 5 ONLY
<!--[if IE 5]>
<link rel="stylesheet" type="text/css" href="ie5.css" />
<![endif]-->
Target IE 5.5 ONLY
<!--[if IE 5.5000]>
<link rel="stylesheet" type="text/css" href="ie55.css" />
<![endif]-->
Target IE 6 и LOWER
<!--[if lt IE 7]>
<link rel="stylesheet" type="text/css" href="ie6-and-down.css" />
<![endif]-->
<!--[if lte IE 6]>
<link rel="stylesheet" type="text/css" href="ie6-and-down.css" />
<![endif]-->
Target IE 7и LOWER
<!--[if lt IE 8]>
<link rel="stylesheet" type="text/css" href="ie7-and-down.css" />
<![endif]-->
<!--[if lte IE 7]>
<link rel="stylesheet" type="text/css" href="ie7-and-down.css" />
<![endif]-->
Target IE 8 и LOWER
<!--[if lt IE 9]>
<link rel="stylesheet" type="text/css" href="ie8-and-down.css" />
<![endif]-->
<!--[if lte IE 8]>
<link rel="stylesheet" type="text/css" href="ie8-and-down.css" />
<![endif]-->
Target IE 6 и HIGHER
<!--[if gt IE 5.5]>
<link rel="stylesheet" type="text/css" href="ie6-and-up.css" />
<![endif]-->
<!--[if gte IE 6]>
<link rel="stylesheet" type="text/css" href="ie6-and-up.css" />
<![endif]-->
Target IE 7 и HIGHER
<!--[if gt IE 6]>
<link rel="stylesheet" type="text/css" href="ie7-and-up.css" />
<![endif]-->
<!--[if gte IE 7]>
<link rel="stylesheet" type="text/css" href="ie7-and-up.css" />
<![endif]-->
Target IE 8 и HIGHER
<!--[if gt IE 7]>
<link rel="stylesheet" type="text/css" href="ie8-and-up.css" />
<![endif]-->
<!--[if gte IE 8]>
<link rel="stylesheet" type="text/css" href="ie8-and-up.css" />
<![endif]-->