From ATI web site:
On August 18, 2004 Valve began the beta test of Counter-Strike™: Source™ through the Steam service. As one of the most anticipated games in years, a select group of gamers will have access to beta test the next iteration of the world's most popular online action game.
Owners of Counter-Strike™: Condition Zero™ and customers who received a Half-Life® 2 coupon with their purchase of a RADEON® 9600 or RADEON® 9800 product are being offered the chance to join the beta test. Coupon holders can visit www.steampowered.com to activate their Steam account and enable them to join the Counter-Strike™: Source™ beta.