Pity that so many still use IE6 despite it being practically obsolete (I even know folks still using Win98!), but not much you could do about it. You could use a conditional statement so that the page uses a different stylesheet if the visitor is using IE6 or below, such as:
Code:
<!--[if lt IE 7]><link rel="stylesheet" href="ie6.css" type="text/css" media="screen" /><![endif]-->
The stylesheet ie6.css is optimized to work for IE6, of course.