PC or Mac? It's the longest-running question in personal technology — along with the Mac itself, the debate turns 27 next month — and probably the most contentious one. A small but noisy percentage of computer owners consist of people who aren't content to pick a computing platform and leave it at that. Instead, they question the IQ and/or taste of anyone who makes a buying decision different from their own. Hence the classic stereotypes: the Windows user as a clueless sucker for punishment, and the Mac fan as a spendthrift fetishist. (Apple has fanned the flames with PC-bashing ads...