Having Trouble Displaying Across browsers

Hi,

I've designed a blog with Atahualpa, but am having trouble getting the three columns to display in a comparable width when I view it in different browsers. it display properly. In Firefox, they are wide, in IE, Chrome, Opera, and Safari, the 2 sidebars become very narrow. If I adjust the make them wider, the center bar gets too narrow in Firefox. The URL is deschenelaw.com. I am a relative newbie, so any suggestions on how to fix this would be appreciated. Thanks.