Pearson usually supplies instructor supplements to texts in Zip archives. Fine. But the PowerPoint slides for Sebesta's Programming the Web 5th ed are in an archive with an extension .sitx. A little searching says this is a StuffIt archive, a proprietary format. Why? Are they going out of their way to make sure some of their customers can't access the materials? StuffIt's free unroller isn't even available in a Linux version, making the 10MB archive useless wasted space on my hard drive.