The are the same size - I made one big rectangle and then just cropped it into three pieces. And the images above the post are just mirrors of the bottom, and they work fine. This is actually the third set of graphics I've made, and it has happened with all three.

Something weird I noticed is that if I remove all the buttons, or if I add them as images only (removing the a href from each of them) it works fine. As soon as I add an a href I get that extra space. I thought it might be a cellpadding issue, but I've tried setting them all to 0 and that doesnt work.

The buttons are the same height as the background image as well.