Basically, for me to compete with what a Mac naturally had to offer, I had to at least be a windows power user (know all the tips and tricks and how to optimize everything for best performance)
I switched over when the Mactels came out over a year ago. I was initially drawn to "spotlight" which offered an instant search of everything on the hard drive (its new in Vista, but its nowhere near as refined), and Expose. Basically, these were organizational features that did not exist on Windows XP. I also liked the fact that I no longer needed to worry about running anti-spyware and anti virus software, giving me more time to concentrate on my own work, not PC maintenance. OS X has always been far superior to Windows XP even on Power PC processors (a 1.6 processors was about equivalent to a Pentium 4 3Ghz). Now that we have Intel processors of the same actual speed, it's just sick.
For the price we pay, Macs are far superior to PC's. We actually pay less, because we don't have to buy a new computer every 2 years. Seriously, until yesterday, I was using an 867 Mhz G4 12inch laptop with 640 Megs of ram, dating back to around the time the Ipod came out, 2002ish. I actually felt guilty about getting my 15 inch Macbook Pro, because I wasn't even sure I needed it that much.
I am now sitting in front of a brand new Macbook Pro with Leopard. I have never felt my computer could be so well refined. Basically, I like Mac because they simplify the computer, and in todays society where we are deluged with mindless amounts of information, its good to have the least amount of complexities as we can. As Apple rightly claims; "It just works". I'm tired of wasting time figuring stuff out, when I could be being productive. Vista is a jumble of un-organization and too much information. Furthermore, Apple laptops are pieces of art. =)