CSS/(X)HTML Cross browser max-width/ min-width (inc. IE6)

IE6 doesn't support the min-width or max-width css properties. But it does understand this : (not W3C valid css)

#container
{
min-width: 600px;
width:expression(document.body.clientWidth < 600? "600px": "auto" );
 
max-width: 1200px;
width:expression(document.body.clientWidth < 600? "600px" : document.body.clientWidth > 1200? "1200px" : "auto");
}