5
I think the main culprit is the image towards the bottom of your site. It's 700px wide by iself. Once you add the side columns, it's going to put it well over 800px. BTW it doesn't scroll for me, IE6 @ 1024 x 768.
*edit: The logo up top is 1000px wide by itself! Say no more. You have to reduce some of thos image sizes!