sanderb writes "The Doom 3 demo is out (on Windows). It does not seem to be linked on the Doom 3 site yet, but is available from e.g. 3D Gamers (includes torrent). Time to see what my FX5200 can do..." Other readers point to Fileaholic.Com and Shacknews.com.
Aren't you glad you're not getting all the government you pay for now?