random background (updated) Options

[Smarmosaur]

mmk, i'm finally getting around to re-designing my website/portfolio thingy. it's definitely going to be more professional and awesome and stuff.

i have codes that will open two links in two seperate iframes when an image is clicked. i also want the clicked image to change, as well as the links to open in the iframes.

here's the test page: http://rockitstudios.890m.com/v3/index.html
and here's the coding on the page: http://rockitstudios.890m.com/v3/index.txt

if you click the first image on the top banner of 5 images, the very top banner (an iframe) will switch to that image, and the white in the middle of the page (also an iframe) will change to black. so, does anybody know how i could go about randomly changing that thumbed image, with the new thumb having it's own links to open in the iframes?