1.try and figure out what is sensible for you to support. Are your web site visitors likely to be using IE6? Probably not.
2. <link href="everything.css" rel="stylesheet"> <!--[if IE]><link href="stupidie.css" rel="stylesheet"><![endif]-->
- eg.
<!--[if IE gt 6]>… for IE versions greater than 6 - eg.
<!--[if IE gte 8]>… for IE versions greater than or equal to than 8 - eg.
<!--[if IE lt 7]>… for IE versions less than 7 - eg.
<!--[if IE lte 7]>… for IE versions less than or equal to 7