I, too, am still a PC user (since the dark, er, DOS days), but come January 15th (and hell, high water, or no new Mac Pro news), I *will* be buying my first Mac.
Frankly, I'm just sick and tired of "dealing" with Windows. I'm a Linux user from way back ('92 or '93), so the UNIX underpinnings of OS X interest me. Not having to deal with viruses and spyware (or the CPU-sucking cycles of software needed to prevent them) is a huge plus, as well as my recent change in focus on using the computer to begin with (i.e. I've taken up using Photoshop and Lightroom as some of the main things I do with my computer - I don't really play games anymore, except for MAME, which I know is available for the Mac.)
I also consider a Mac an actual investment because of the cost (Mac Pro = big $$$), but it's a machine I won't likely need to upgrade for many years (especially with 8 cores...even Photoshop CS3 doesn't take advantage of THAT many yet, I don't think.) -- With a PC, you can buy the components cheap and get some good deals, but at the end of the useful life, you either make incremental upgrades or (more likely) just throw the damned thing away (or sell it to a friend for a few bucks - that's all it's worth.)
Macs, on the other hand, have (what I've seen) relatively crazy resale value, where you might actually make back nearly half of your original cost (sometimes slightly more) if it's a good system, loaded with features (and RAM.))
So I can't wait...only 2 more weeks until I'll be ordering my new system!
-Bryan