Stung by criticism for its decision to create a device based on Windows Mobile, Palm last week reiterated that it would continue supporting rival Palm OS as well. "I'm concerned by the number of posts I've read that suggest that Palm's support of Palm OS is either wavering or short-lived," Palm CEO Ed Colligan wrote in an open letter to Palm developers. "It is neither." Colligan said that the decision to go with Windows Mobile didn't mean that the company would abandon the simple Palm OS system that the company first rode to success. In the future, he said, Palm would release devices based on both systems. The situation is vaguely reminiscent of Apple Computer's migration from the Apple II line to the Mac, I guess, or Commodore's transition from the C64 to the Amiga. I think we all know how those changes worked out for the legacy system du jour. I have little doubt that the Palm OS is excellent. I also have little doubt that it's on the way out