Offset alignment of Prosite website templats

During the registration process of my Prosites signup page, I have four images of the New Blog Templates websites for the visitor to view. One of them is wrapping to the next line. I created the images with the same width. Attached is a snapshot of the page.
Here's the page: http://wordsandwriters.com/wp-signup.php

How can I get them to line up properly?

Thanks, JOe.