Sidebar Help

I've been sitting here for like three hours trying to figure this out. It's probably just a stupid mistake, but if someone could get to the bottom of this I'd appreciate it!

I'm updating my site (http://halouvre.sacredicon.com) so that it's easier to update. I made the thing when I knew next to nothing about HTML, so the code looks like it's straight out of 1995. Anyway, a part of the new site is located here. Now, see how the sidebar messes up the position of the Gallery? When I take it out, the problem goes away though. Did I do something wrong in pasting my new site around the gallery or is it something else? If anyone could figure this out, I'll give you a cookie!

Thanks!

KD_1