Since I had a hard disk die on me, I figured I could easily try some other OS (I usually run Ubuntu). Turns out that Ubuntu flawlessly recognizes my video card and monitor (X11 works right out of the box), and none of the other systems I tried gets anything working (I tried CentOS and FreeBSD). In my now working version of Ubuntu I cannot find a configuration file with information I could try to use with one of the other versions, which makes me guess that it just detects the hardware every time. Can I extract its choice for drivers and configuration options somehow (so I can try these same options in the other systems)?
Xorg -configure (run as root from a text console) produces a configuration file that should be equivalent to what Xorg autodetects.
But that may not be enough, because it's likely that the reason your video card works in Ubuntu is that it has more recent drivers, or installs proprietary drivers that the other OSes don't install. Look in
/var/log/Xorg.0.log for startup messages (that's the Ubuntu location, it may be different on other OSes), and see where they differ.