[Mr. Blonde]

They are supposed to last up to 7 hours on a charge and have a useful life of 5 years before needing to be replaced. Replacement apparently costs as much as a replacement for Blue Highway’s Compaq ($130). The only difference being you have to drop the Apple off at the Apple store for a few hours or send it to Apple for a few days. Some will consider that a worthwhile trade-off for the increased size and longevity. I would imagine most people are looking for a new laptop at 5 years anyway.

[Cyber Liberty]

I've usually broken mine in three years. That's about how long my last three laptops have lasted. I can be a bit hard on them at times, I guess. Just under the three-year time limit on my extended warranty.