Erin did a great job explaining the differences. I started out on a mac 19 years ago and about 6 years ago, I decided to get a PC for my home computer (my office computers are all macs) so my hubby could learn computers (he had PCs at his work). It nearly DROVE ME CRAZY! Oh, and I'm typing this message on my home mac now!
You don't have to learn macs - well, if you are used to a PC, then yes, you have to unlearn the PC "way". Mostly, you just let the mac "do its own thing". I loved when Erin said, "you plug in your camera and the mac figures it out". This is exactly TRUE.
I know NOTHING about how computers operate and I've been mac literate since the day I turned it on in 1988. It is so easy. But, I have heard my PC friends say, it is a pain to "unlearn" PC ways. However, if you just let the Mac "do its own thing" you don't have to unlearn anything - OK, that's not exactly true, but it feels that way.
The part about the viruses is partially true - it is true that Macs don't get viruses, but not because the CAN'T get them, but because there are so few macs, the hacks don't bother creating mac viruses. It may be true that they are safer from viruses, but I guarentee if some hack wanted to create a mac virus, they could!
It is also true that almost everything you need comes already installed in the mac - installation of programs is a breeze - YOU do nothing, except stick the disk in and let the mac "do its thing". You will need a word processing program, eg. MicroSoft Word - but that is about it, unless of course you are into graphic art or something like that!