FIX CSS <!--[if lt IE 8]> in IE

How can I use this:

    <!--[if lt IE 8]>
    <style type='text/css'>
  #header ul#h-menu li a{font-weight:normal!important}
    </style>
    <![endif]-->

If I remove <!--[if lt IE 8]><![endif]-->, above code'll run good in IE 8, but if I don't do it, it wont run. Help me with fixed IE, so that I can use above code in all IE versions.

I want the code #header ul#h-menu li a{font-weight:normal!important} to run only in IE.