Hey there,
I was looking at the two themes available, and the one called black Candy looks bad in IE6! There are margin issues with the side menu and others...I looked at the "themes" folder and the css and there is an IE6 css doc with some hacks, but they aren't right...just look here in IE6:
http://demo.silverstripe.com/
and here:
http://demo.silverstripe.com/about-us/
eek! I don't have IE7 but why isn't the css correct right out of the box on this theme?