Greetings all, I'm a proud owner of the final PPC, Powerbook G4 15" 1.67GHz. I've taken this thing through college and graduation and for 4.5 years, it has been my workhorse. Sure, it gets very warm/hot, Videos on Hulu are a bit choppy, I don't have the camera on the top, I'm stuck on Tiger, I'm on my 2nd battery, 3rd power cable, and I think one of my fans are broken. Sure, the new Macbook Pros (esp that 13in) look absolutely gorgeous and a purchase now would be a substantial upgrade in every category. But My question to all of you is not the typical, "Should I buy now or wait" but more, when does desire become necessity? There are countless "Should I buy now or wait" questions posted on this website and the usual answer is, "If you need it now, buy it now. If you can wait, then wait." What defines "need?" My mom still uses her Dell from 98 and although I tell her to upgrade, she responds with the valid point, "Why upgrade and spend money if it still works?" What is the tipping point for all of you that drives you to purchase/upgrade? I'm sure for some of you it is the need to have the latest and greatest, but for those who try to maximize the use and value of each machine, given that it still works even with a few flaws, why/when did you upgrade? Finally, what do you do with your old machines? Do I sell it on eBay for 300? Do I keep it lying around as a back up?