Hurray! I finally got the brightness buttons working on my
laptop. Ever since I got the laptop the brightness buttons would
work fine until I started X, then they wouldn’t work again. Was
poking around and looking at the laptop market tonight and found
a page that mentioned that they had the same problem and they
fixed it by adding:

Option "AGPMode" "4"

To their X Device section. I’m not sure this card is even a 4x agp
card, but adding that in there seems to fix the birightness
button pretty handily.