Not sure what's off... padding, or something? (cross-browser display difference)

My first page using CSS, and I’m running into a little problem:

http://recoil42.ath.cx/gamerlogo/

What it looks like, and SHOULD look like, in Firefox 2.0:

…And in IE6:

Look on the right… notice the problem with alignment in IE6? In FF, all the divs line up, and go perfectly straight down the page. In IE6… “uh oh… what’s this? alignment is all screwed up!”

Can anyone tell me what’s going on here? I can’t figure it out…