I have to scroll horizontally with the left column intact, so I'd rather not have it shown with the picture threads.
I'm viewing with a 1440 X 900 screen.
Upon further study here, I'll bet you're using the UBB stock style (the yellow one), is that right?
It seems there's something quirky with the post window itself if a 800px picture (or a quote) is in it. Even at 1600w it has a scroll bar even though there's plenty of whitespace to the right.
I'll check into the style code later and see if I can figure out what's going on there.