The strangest thing happened. Apple returned my computer with a disk in the drive. It contained a lot of utilities, diagnostic tools, and system updates. I didnt use the utilities, but one looked as though it changed the information concerning the processors or computers s/n. I though that this would be an external process, or at most something that couldnt be changed. I returned the disk along with the then sporadic CD tray. (I think that the disk damaged the servo in transit.) They never sent a thank you letter, but were anxious to get the disk back. It was one of the fastest AppleCare resolutions that I have ever received. Still, no thank you.
If it looks to be a new unit, then I dont think that there is an easy way to tell. Some companies stamp something into the back or under the battery cover. You might want to look at the first digits of a few PowerBooks and compare them to a factory referb. I think that if Apple refurbishes the unit, it should be good as new, less cosmetic blemishes. Other companies my claim to refurbish units, and thats where it would get sketchy.
I would buy the AppleCare. Every extended warranty that I have purchased for a laptop has paid off. Nothing is worse than having your computer go down, especially if you cant afford to fix it. I have never lost money on AppleCare. Its worth it if its your primary tool for work and/or school.
