I had a mac for 7.5 years before I got a new one. It worked with no issues. Never had a virus. Never had virus protection. Barely slowed down at all. The only problem way it got to be so old they didn't update it anymore. I just bought the newest MacBook Pro and like it. Ive owned an HP and Dell and they were alright.
Much cheaper. Better performance. More customization. More games. More apps. More programs. Won't be "old" in 5+ years. And so on...
Macs are over engineered as they go obsolete before they wear out.
http://cdn2.alphr.com/sites/alphr/files/styles/16x9_640/public/images/dir_35/it_photo_17518.jpg?itok=peQy9OpL This picture explains it all.