The latest advertisement from Apple promoting the benefits of a Mac versus PC states: "Ask not what Vista can do for you but what can you buy for Vista?". Saying that even a simple printer will not work and that you will need to buy a new one.
Well, not only will your printer work with Vista. You have to ask yourself what kind of backwards compatibility does OSX offer versus Vista.
When OSX showed up, its compatibility was simply disastrous. You had to run MacOS classic inside an emulator, a very slow and painful process. Not only did all the old software not work, but Apple excluded a huge number of models from the the OSX compatibility list since all but the absolute newest PowerPC models had enough horsepower to run the new OS.
But that was just the migration from MacOS classic to X right? Nope, on every point release (or is it non-free service pack?), Apple keeps on dropping older models with extreme prejudice.
Finally, what about all those people who bought a PowerPC based Mac instead of an Intel based on? Surely Apple will keep on releasing software for them right? Yeah, don't hold your breath.
The truth is, Apple may make fun of Microsoft for its compatibility woes with Vista but underneath it all, Apple customers are terribly jealous of the compatibility offered by Microsoft to its customers.