In the interest of truthfulness (and avoiding trolls), I'll try to be very clear. Also, keep in mind that everything I say refers to Mac OSX.
i heard that they never get virus....why is that?...also are they
spyware free too?...or is spyware the same thing as virus?
While it is true that no virus for Mac OSX has yet been discovered in "the wild" (i.e. actually hurting people's computers), it is possible that one could exist in the future. That said, Mac OSX is in some ways a less fertile host than Windows, as it is better configured. There are fewer hooks between the browser and the OS, dangerous network services are turned off by default, and user permissions are employed more judiciously.
Spyware is not a virus, it is software that makes it onto your machine and then spies on what you are doing and reports it back to someone. Most spyware programs are downloaded by the user by accident--either in the course of downloading something else (like a game or screensaver, etc), or in an e-mail attachment, etc. Again, Macs can theoretically host spyware, but PCs are more fertile ground, presenting fewer obstructions to the installation of spyware.
Finally, there are way fewer Macs than PCs, and correspondingly more programmers for PC than Mac. As a result, PCs make a much fatter target for viruses or spyware, AND there is a much larger base of programming knowledge out there to write such software.
i'm going to buy a new computer and want to know the facts...
i've been a pc user all my life but maybe its time to change?...
The facts are that while Macs are not invulnerable, they make for much safer computing right now for two reasons:
1. They are well configured for security.
2. They are not targeted by most virus/worm/spyware writers.
Finally, in terms of speed or capability, Macs keep up just fine with PCs. Most things run just as fast (especially if you have lots of RAM). The network and software compatibility with PCs is very good as well.
I would recommend getting a Mac. I did after 3 PCs and have not looked back--I love it.