I went to your site and then looked at teh source of a generated page. To find out what was happening I made a copy and stored it locally. I then, using the local copy, started deleting the CSS and after i deleted ALL the css I started deleting what ever was there. Suddenly the scroll bar was gone.
I undid the last bit and found you had a hardcoded reference to another style sheet
<link rel="stylesheet" href="http://lafollettegallery.com/home/wp-content/themes/atahualpa/style.css" type="text/css" />
I then, using the address, displayed this style sheet and in side see:
Theme Name: Atahualpa
Theme URI: http://wordpress.bytesforall.com/
Description: Build your own unique, professional and browser-safe WordPress theme: Over 200 theme options, drop down menus for pages and categories, fluid or fixed width layout, 1, 2 or 3 columns, rotating header images, auto image resizing, integrated Feedburner form, 4 extra widgets and more. WP 2.2-2.7 and WPMU. English plus DE, HU, PT, CZ, SI, TR, FR, PL, NL, BG, IT, VN, JP, ES. Support at the <a href="http://forum.bytesforall.com/">BFA WP Forum</a>
Author: BFA WebDesign
Author URI: http://www.bytesforall.com/
so somehow you are pulling in the style.css from 3.2 along with the current styling.
I have no idea how or what you have coded, but that's what is happening.