Chasky--just a few items to keep reminding yourself of when you feel like "falling off the wagon:"
1. Viruses for Windows: tens of thousands, a large portion of which can still effect current versions.
Viruses for Mac: tens, most of which haven't had any effect since OS 8 and up.
Viruses for OS X: None that I know of.
2. Security for Windows: think swiss cheese; dozens of new "critical" exploits every week. Often months go by before any sort of fix is released...which often causes even worse problems.
Security for OS X: one or two oddball issues per year, so far, each of which has been swiftly and cleanly addressed, often within a day of being discovered.
3. "Product Activation" for Windows: gotta get Uncle Bill's permission to make major hardware changes, and you don't actually own the software, you're renting it.
"Product Activation" for Mac: you pay for it, you own it. No registration codes required for the operating system or any of the bundled software; registration code is restricted to the Heavy Duty software like Final Cut Pro, etc.
These are just a few things which come to mind right off the bat--the low-hanging fruit, no pun intended :) I'm sure others (hey, Bill!) will come up with dozens more.