I'm currently on a nine month old 17" PowerBook G4 (1.67GHz, Hi-Res) with 1.5Gb of RAM and the 120Gb disk.
Originally at the beginning of the calendar year I bought a hi-res 15" PowerBook, only to find that the battery wouldn't take a charge. I took it back to the retailer and exchanged it, only to find that the next 15" PowerBook's battery wouldn't take a charge either. This cycle repeated for four 15" PowerBooks. At the time I was reading about the problems with 15" batteries and the weird screen artifacts that plagued that run of 15" PowerBooks. So, after walking back into the retailer with the fourth 15" PowerBook, I decided to go with a 17" instead, given that the Apple discussions forums reported none of those problems with the 17". Alas, while I initially thought the 17" were too big, I am now totally stuck on the 17" display's real-estate and resolution. And, I have to say that my 17" PowerBook has been bulletproof -- it gets used about ten or twelve hours a day every day, and only gets rebooted about once a month on average, and then only for good reasons, not because it's hosed or anything.
So, my ship-date on my MBP C2D 17" 3Gb/160Gb is six days away and I know that shortly after I've spent time with my MBP, I'll have to part ways with my less than one-year-old PowerBook, and find it a good home, given that I can't justify keeping both.
I can only hope that the C2D turns out to be as reliable as my PowerBook.