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.
It is better to give than to lend, and it costs about the same.