There was an interesting announcement today which came directly from Apple: The new Intel-powered Macs (MacBook Pro, and the 2006 iMac) are able to boot natively to Windows XP using an Apple utility called Boot Camp. This means that if you're a Mac fan, but there's this one piece of software that you HAVE to use, you can still buy a Mac and run your software natively on Mac hardware. This also means, however, that you get to deal with all the insecurities which are part and partial to the whole Windows package. You also have to actually purchase Windows XP ($194.99).
Still, this is a big step. For many people on the fence, this is likely to be the feature that will convince them to purchase a Mac. Shawn's crystal ball says: lots of users with this "dual-boot" setup with Windows and Mac OS X on their Mac. The Windows side will be totally screwed up with your choice of malware, while the Mac side will be running just fine. People will choose to use Mac OS X instead of fix Windows.
Boot Camp is currently in public beta, which means it's free to download, but use it with a grain of salt because it's not officially a finished piece of software. It will be officially released as part of Mac OS X 10.5 "Leopard" whenever that comes out (probably early 2007).
In any case, I've heard reports of it working as promised. The next step is to have both operating systems running simultaneously, so you don't have to restart your computer to get to Windows. Also, look for Linux to be available in a similar configuration.