Text size increase in browser wrecks page

[telly]

I built out a page in layers and converted to tables with images and caption layers on both sides of a text layer. When I increase the font size in both ie and netscape, the images stretch along with the increase. Can I "lock" the image layers somehow? I've fiddled with setting the layer's size to % and a hundred other things but nothing seems to help. This is my first page and probably an obvious newbie question, but I couldn't find any info anywhere. If you would like to see the page, it's at

http://www.brenhamrentals.com/

Additional comments eagerly accepted as well!

Thanks!