My G3 dual USB iBook is on its last legs. The drive died last year and I replaced it, but that was probably a mistake. Now the display is getting dimmer and the hinge is very stiff; these are known symptoms of a design defect that affects iBooks.
The G3 iBook has about a three year lifespan with average use. I think I fell a bit short of that, but I used it very heavily. Three years is the range of AppleCare coverage; if AppleCare service was higher quality I'd get it for my next iBook. Alas, it is not.
I'd hoped I'd make it to the Intel ibook, but the roll out of the Intel MacBook Pro has been so troubled I figure I'll just buy a G4 iBook. The old one may end up attached to an LCD panel in the kitchen, or it may just be junked.
I wouldn't mind a four year lifespan for a laptop, three is a bit short. My old PowerBook 165 lasted about five years, but nobody makes anything that reliable any more.
Update 4/2/06: Macintouch has the best information on this. Nobody mentioned iGlide in that query, it does show up in the few remaining Apple discussion posts on this (they archive older posts and there are few G3s left). WD-40 is a bad idea, it destroys the plastic. I wonder if iGlide is just Teflon spray but I may give it a try. I'll try loosening the bolts slightly to each side of the hinge then spraying it.
Update 4/9/06: Tried iGlide. It had no effect. The instructions require one to remove the rubber feet and loosen the associated screws, that broke 2 of the 3 feet. I sort of expected that from past experience, crazy glue holds them on now.
Update 4/11/06: Oddly, the function is now improving. It just took a couple of days. Crazy glue works well on those iBook feet ...
Update 5/11/06: Still works fine. I sent the company a note saying how pleased I was. I did mention the feet braking, and they sent me a set of replacements. The crazy glue will likely last the lifetime of the iBook, but that's impressive. They also gave me a strong hint of where the lubricant comes from. No, it's not WD-40 -- that would dissolve the plastic. I won't repeat it (sorry), but the source is consistent with the successful results I saw.
Update 11/18/06: The hinge is again in bad shape, and now the cracks are growing and the alignment is off. The treatment gave me 6 months, time enough for the MacBook Core Duo 2 to come out. Worth it really, but not a cure. I suspect the hinges go when some teflon like surface wears off; they probably can't be cost-effectively repaired. I could probably reapply and get some more time, but instead we leave the iBook permanently open. It's not bad for carrying around the house.