Microsoft's super hit Halo 2 has quickly passed another milestone, selling more than 5 million copies in just 3 weeks of availability. That means Halo 2 has sold almost as many copies as the PC and Xbox versions of the original version of Halo combined. More important, perhaps, Xbox Live subscribers have logged a cumulative 28 million hours (think about that for a second) playing Halo 2 online. Typical users spend over 90 minutes playing the game online during each play session, Microsoft says. And I thought I was obsessive! I just spent a week to finish Half-Life 2. Apparently, I'm a slacker