Ha! I figured it out! In the CSS I simply needed to add a width parameter.
Original code:
#upprev_box a.upprev_thumbnail img
{
border:0;
float:left;
margin:0 10px 5px 0;
After I added the width:
#upprev_box a.upprev_thumbnail img
{
width: 70px;
border:0;
float:left;
margin:0 10px 5px 0;
Here is a screen cap: https://dl.dropbox.com/u/16423991/Screen%20cap.JPG