Do macintosh computers get viruses?

They can, yes, just not as frequently as PC's. They're not bulletproof but they seem that way because there's less malware in circulation for the Macintosh due to there being less Mac users in comparison to the PC. Macs are rising in popularity so we'll be seeing more and more viruses being coded for the Mac in time. Right now most computer users are on the PC using Windows so it would make more sense for a virus writer to code up exploits for Windows; get the most bang for his buck.