There are plenty of reasons to use a Mac; great software and hardware, the iPod, but perhaps the best reason is security.
It's pretty well known that the Macintosh is a great platform because of the lack of viruses, trojans and malware that targets it. It's one rare case where less market share is actually good for the platform. There isn't a huge crosshair painted on our backs by increasingly creative script kiddies dying to see their next exploit splashed on the front pages.
Another case in point for going with the Mac is the recent DRM tactics employed by SonyBMG. The entertainment giant has taken a huge new step to protect their music content: installing rootkits on Windows-based PCs. According to Wikipedia:
"A root kit is a set of tools frequently used by an intruder after cracking a computer system. These tools are intended to conceal running processes and files or system data, which helps an intruder maintain access to a system for malicious purposes"
A SonyBMG-produced Van Zant CD, ironically called "Get Right With the Man," contains a small piece of code that, after clicking through an EULA, used a sophisticated cloaking technique often used by virus writers to make it difficult to hack the content protection on the CD.
Although Sony has issued a patch for the malicious code, it represents a disturbing new trend by content providers desperate to lock down their content—at the expense of your privacy. Want to avoid all this ugliness? Buy a Mac. They're impervious to the Sony rootkit and a lot of the other nasties out there.