Gasp! Someone has had the temerity to state that Macs are PCs too and are vulnerable just like them! Despite the horrible ads from Apple it is being brought to light that Macs are increasingly vulnerable to viruses are (unless packaged with SSDs) are in need of a good defragging from time to time.
Theo Valich, has a nice little piece in his blog where he braves the scorn and potential flaming from the Apple Zealots by making these ugly little secrets known.
Read more here.
According to Stephen Withers of ITWire fame, Apple recently started to update its knowledge base recommending that users start using anti-virus software for their OS, the Mac OS X. Sadly, we see this as a beginning of the trend, and it is only a matter of time before Mac users start to need complete internet protection from 3rd party software manufacturers.
Second misconception is that you don't need defragmenting the hard drive, because the "system does not need it". EVERY hard drive (sans SSD) needs defragmenting in order to put frequently used files at the beginning of the hard drive. It is a the way how conventional hard disks work (they're analog devices, after all), not file system based. There are some efforts in fragmentation-free file systems, but Apple isn't one of them.
Back at the day, I was surrounded by Macs and users that kept them at "sacred ground", banning my test lab or IT department from fixing them - yet we had to suffer through various instabilities (bombs were an everyday thing, especially if 2-3 software apps were loaded at the same time). After some Apple zealots left the company, all of the hard drives were defragmented and these machines gained a second life.
It was sad hearing brand new Mac Pros "scratching" the hard drive in every-day work - personally, I recommend TechTool Pro as the best collection of utilities for Apple platform. Alternatively, you can use iDefrag.