I'll avoid the obvious suggestion of moving to CSS instead of tables... That's what everyone will tell you, and it's true.
Anyway, I looked at the graphics you're using to create the site and I think sbr2.gif is a bit too short. Also, the bottom graphic, bc.gif, has too much white at the top of it and seems to be pushing it down a little too far.
Looking at the site in Mozilla, that's the only graphics-related error I see. In IE, I see two gaps. One on the left and one on the right. But you didn't specify about the gap. What are you seeing? One gap (on the right) or two (on both sides)?