Windows: consumer-oriented. Tightly integrated. Disadvantages: vulnerable to viruses. Tightly integrated. Slows down after running 24 hours. Very little actual control over your files (they get written all over the disk haphazardly and the file systems you see even in MS-DOS have little to do with reality necessitating frequent defragmentation). Pricey for what you are getting. 

Mac OS X: tightly integrated hardware and software. Optimized for presentation graphics. Modular operating system (Unix) allowing for greater control of who or what writes to system files (safer). Gives you more control over your files and when your computer accesses the internet. Disadvantages? Pricey by andy standards: often a value but never a bargain. 

Linux: Advantages? Modular Operating system (Unix). You can have a truly free, nonproprietary OS in it but Microsoft has been using its political clout to make it more and more difficult. Inherits a tight security system from Unix, and selinux form the NSA has made it more secure. Total control over files and internet access. Disadvantages? Shows its technical origins and derivation from Unix in things like tar (short for Tape ARchive) cp (copy without the vowels) and other command line tools which are often used as back-ends for GUI programs.
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