Not a Member of the Monoculture
It's well known that infections spread best in monocultures.
Computer viruses, trojans and worms would surely follow that maxim.
Stay out of the monoculture, turn off all updates (and sometimes manually patch the occasional really nasty ones) and you'll be an unattractive target for the scriptkiddie's bot-botnets.
Not to mention the bloatware listed above requiring more and more memory and eventually a hardware upgrade....