Sounds like a padding issue. IE doesn't allow padding on images so it ignores it. But when the rollover has a different padding than the off state, the width of the image will change, thus the position.
Thanks Jack, I looked over the CSS and found on the large photo the margin set to 3 and on the hover set to margin 4. Made them both 4 and it's fixed now. Strange how it got set this way, it's a new install.