When Is There a Good Time to "Switch" to Apple?

AllNines asks: "With all the hype of MacWorld and the compelling keynote given by Steve Jobs about the upcoming Tiger and Spotlight, I am thinking about 'switching' (Linux user since '97) but I am not sure the time is right. It seems like the PowerBooks are getting very long in the tooth and the iPods are due for a major rev. When is the right time to jump on the Apple ship? Am I going to get burned by a sluggish overpriced laptop that is updated next month?"