I had my very first Apple failure yesterday. And it was the hard drive in my 27" iMac (1st Gen) a little over 2 years running flawlessly. I had noticed a bit of flakiness last week and didn't give it much thought. But it started doing it more often. Pulled up Disk Utility and it showed a SMART error with the message to save files and replace drive.
I did a SuperDisk clone to my external Firewire 800 drive, ran for a day off of that with no issues. Took it to the certified Apple service guys nearby and they will have it ready on Monday they think. I have Applecare so no charge for the service.
After over 10 years with Apple, this is the first computer of theirs that has given me any problem whatsoever.
For those that need this kind of service, if you have a cloned backup, then you can save the service center and yourself some time by telling them they don't need to put on an OS other than enough to do testing.