A few months ago, I had resigned myself to the fact that I’d probably never get my system to do accelerated 3D graphics while still having both monitors on.
All that has changed thanks to Google. And a bunch of mailing lists and FAQs, and other linux hackers who have the same video card.
For reference, I have a Radeon 7000 (or Radeon VE) dual-head AGP video card. And Unreal Tournament works great. I’m still having some problems getting Half-Life to run in Wine, but that’s mainly half-life’s fault: I can’t get it to run in 24-bit or 32-bit color.
Note: you will need the newest DRI version, from CVS or otherwise. There are some Debian apt sources for that on page 3, if you’re using that flavor (x86 only, sorry).
Oh, and if you have a serial Wacom tablet (I have a Pen Partner 4×5 tablet), there’s some configs in here that also work. Well, they worked when I had Xinerama enabled (before I managed to get dual-screen 3D to work). I need to dig my stylus back out and see if it works with this new config, but these settings DEFINITELY work if you have a standard Xinerama setup.