Bought my laptop back in 2008. I've replaced the battery, and upgraded the OS (not reinstalled). Otherwise it just kept chugging away. (One of the reasons I laugh when our fearless leader has replaced his entire computer at least twice (by my memory - which is not to be relied upon) in the same time frame).
However last night it died big time. It froze in the middle of some work, then refused to reboot. Since I have time-machine, I am not too concerned - no matter what I have to replace to get my computer working again, I know I have not lost data.
I go into the local Apple store today. One of the techies tries everything she can - boot off network, boot off alternate graphics card, boot off firewire, boot off USB - no joy. I looks like the logic board is fried.
A logic board should not die in 5 years. Even though I do not have an explicit warranty on any problems I cause, there is still the stock standard Apple warranty on logic board. She is all apologetic - it may take up to 5 days before I get my computer back from their service agents. I blinked twice then told her: if you want to take my brick away, and give me back a working computer in 5 days for zero cost to me - I am not going to complain!
Side note - the woman sitting next to me had purchased a refurbished iPod from Apple, and brought it in because the case was cracked. The techie helping her was also apologetic - we can replace it instantly with a brand new iPod, but since ours are not refurbished, the cases are different - if you have purchased a cover for the faulty one, it may not fit the brand spanking new one.
So the bad news is that the spare computer I have at home is too low powered for almost anything. Online surfing is all that computer was designed for.