abc_ua так в IE6 работает:
var e = document.getElementsByTagName("img");
var width = 200, height = 300;
var w, h, hi, wi;
for (var i = 0; i < e.length; i++)
if (e[i].className == "ph_cat")
{
w = e[i].width;
h = e[i].height;
hi = h * width / w;
if (hi <= height)
{
e[i].style.width = width +'px';
e[i].style.paddingTop = (height - hi)/2 + "px";
e[i].style.paddingBottom = (height - hi)/2 + "px";
}
else
{
wi = w * height / h;
if (wi <= width)
{
e[i].style.height = height +'px';
e[i].style.paddingLeft = (width - wi)/2 + "px";
e[i].style.paddingRight = (width - wi)/2 + "px";
}
}
}