Half a dozen of one, six of another. Buy what you are comfortable with. Nothing wrong with Mac OS. But the notion that Mac is "better" than Apple comes from the days of Windows 95. Windows 7 and Windows 8 are as trouble free as any Mac. And there is more software available.
Also the notion that Macs are somehow impervious to malware and other attacks is gross misinformation. They just aren't targeted as much.
Windows is pretty secure. So much so that malware writers no longer look for flaws in that OS, they use 3rd party software like Adobe Reader, Flash player, and JAVA. Guess what? There are versions of these that run on all popular OSes.
So again, buy what you are comfortable with. One is not better than the other.
Oh, BTW, I've been a systems administrator and have worked with many computer OSes for the past 18 years.