Help with small layout glitch.

Hi still feeling my way along with HTML and Javascript

I've encountered a small spacing problem in a layout I've just started
working on, and for the life of me I can't see anything that is causing it.
It occured just after I added the mouseover script.

As there are quite a few jpgs, I've set it up and here is the link:

http://www.good4mail.com/TempTest/_Template.htm

If someone could explain what is causing the line break and how to correct
it, I would be very grateful.

(none of the links go anywhere yet, and I know I haven't protected the
javascript for old browsers, and no javascript enabled yet)

Thanks
Jenny