A good day for demos (or for people who are broke). Grab the Rainbow Six Lockdown 519 megabyte demo from one of these fine mirrors:

The demo includes a singleplayer mission (South Africa) and a multiplayer map (Prison). The singleplayer mission will let players play a ‘campaign mission’ on two different difficulty modes: ‘normal’ or ‘challenge’ as well as in co-op. The multi-player map can be played in ‘Team Adversarial’ game mode. There are 17 weapons available in the demo (42 will be available in the retail version), and all the equipment and grenades are available for both single and multiplayer maps – while the Custom Character Creation and usage is available in multiplayer.

– 3D Gamers
– Gamers Hell
– File Planet (Free registration required)
– Worth Playing