My website does not center when viewed in IE yet when I view in firefox it is. Not a big deal but what is...

In IE my center content on product listing pages and within my shopping cart and checkout pages is being cut off. For instance when you are checking out and reviewing the order before submitting you can't even see the entire total. I even tried to remove my right side boxes to make my centercontent box bigger and it still cuts it off just the same. How do I fix this?

my site http://www.divamomdesigns.com/zen-cart