I've just visited your link with my IE6 and it renders almost absolutely the same as in my FX 3.5.2.
The only difference is that "monster add space" is not rendering in the middle. But that's NOTHING, might be some wrong nesting or dimensions missing. Otherwise they render identically and if IE6 is handling it perfectly- I don't see any possibility that IE8 is not rendering it identically.
Otherwise you should ask you template provider, and ask him why?