The stuff you posted is what I was hoping to see. Now if you don't mind answering a few more annoying questions We'll see about getting those new ATI drivers installed.
In your /etc/modprobe.preload you might want to try putting a # in front of all of the amd64-agp lines, rebooting and trying aticonfig --initial -f again.
In Synaptic... What repository do you use?
Are you fully updated? (I know it's been asked, but I don't remember reading an answer)