As with all computers, the major contributors to computer death are:
Electronic Static Discharge (ESD)
Clumsy operator, or user damage.
Most chips are susceptible to heat damage. For example, first generation
pentium computers could not be faster then 90 mhz, because they would
overheat and die. For a lot of computers, the manufacturer may have relied
natural heat dissipation
a power supply fan
a heatsink, without a fan.
a heatsink with a fan
Whenever you opening your case to add a card or do any work, ground
yourself. The best way is with an ESD workstation or ESD wriststap connected
to your work. If nothing else is available, at least grab firmly any metal
in the case
All computers contain their analog/mechanical parts, most often failures
occur because of a failure of these parts, causing intermittent problems.
The most important thing for analog preventative maintenance, is to remember
computers like to be kept clean and dry. Your computer can certainly use an
occasional cleaning and a once over to ensure it is kept at it's best.
The heart and soul of your computer, "the electron, the bit...", harder to
diagnose, but at most times the hardest to fix. Often damage to a digital part
occurs well after you've repaired analog problems. If you're lucky, you've
aquired spare parts of the major boards and are simply swapping out. If not
then you have the challenge of finding parts, or paying a high level techie
to search the board with a voltmeter and logic probe.