It was quite easy for me. The interface is quite intuitive, of course it was designed that way from the beginning. My biggest problem was learning new keyboard shortcuts. People report quite good results handing the elderly a Mac and having them up and running with minimal instruction.
The only reason Macs don’t get viruses is that virus-makers want to do the most damage they can for the least effort
Well, there is the hardened UNIX architecture. There are 50 million Macs on the market, most without any protection. That's a big, juicy target, especially considering that the demographic tends twoards people with more money to steal from. So far the most we've seen in the wild is the rare trojan that requires an admin password to install. Almost everything else has been in the lab, usually by created by those trying to sell antivirus products.
Windows Vista bombed because its hardware requirements pushed the limits of what was available.
Vista bombed because it sucked. The development effort was plagued by mismanagement and changing scope so much that it had to be suspended and eventually restarted from scratch near the end. The bloated hardware requirements were just an effect of the core problem, and exacerbated by pressure from Intel and poor advertising strategy. Another was trying to tack on Mac-style security to a very poorly designed and factored security system, which resulted in UAC popping up every other time you clicked on something. One example going back before XP, if you want to prevent someone from changing the clock, you also prevent him from opening the clock at all, because the entire thing was under one privilege set. Mark Russinovich's complete refactoring of the whole security system is one of the reasons Windows 7 is so much less annoying, almost Mac-like.
. Windows 7 is more scalable, and stopped the trend of continually upping the ante of the hardware needed to run it.
As an example of how bad Vista was, Windows 7 will run well on hardware that would have had Vista crawling. When people with a Vista machine ask what they can buy to make their computer faster, my first suggestion is usually to wipe it and install Windows 7.
Apple is going to miss Vista.