Apparently bent on bringing the Internet to a halt in what's already a trying time for download sites, Activision has released the single-player demo for Soldier of Fortune II: Double Helix for
download from FilePlanet (registration required). The whopping 136.9 MB demo includes two levels from the full game, Columbian Jungle and Seaward Star.
Update: There are mirrors on
FileFront,
3D Gamers and
Fragland.net (Belgium).