You're sitting at your workbench, carving a piece of wood, and your friend comes over. Instead of saying "Hi, how's it going?", he says, "dude, you should totally buy Craftsman tools, they are really sturdy." You think, gosh, I'm happy with my Ryobi tool set I bought. So you say to him, "but I like the friendly grip of Ryobi while I work." So your friend says, "I can't believe you'd use such a crappy product. My mom has a Ryobi drill and it's broken all the time." You tell your friend to shove it up his a$$, you like Ryobi and you're happy with what you got.
Later that night, you decide to help a different friend out with a project he's working on. You bring your Ryobi drill set and screwdrivers to help. When you get there you two start working on the project, but you soon find out that your power supply doesn't work with his Stanley drill. You get upset because your friend doesn't realize that the recharging batteries that Ryobi has are much more efficient and his Stanley power tools aren't as good as yours, even though they are much more powerful. Sure, you could use his set, but you don't like the feel of the grip as much as you like yours, so you tell him you can't help him with his project and drive back to your house.
Did that just sound totally stupid? If you said "yes" you have no reason to be a MS, Linux, or Mac zealot. You have no reason to ever put down someone's OS they choose. You have no reason to bash an OS.
If you said "no", then you need to stop being so confrontational and get a life.
Please, why can't people just accept that others will use a different OS, and that they may in fact LIKE Windows or OSX or FreeBSD or SCO Unix or Ubuntu or whatever OS they decide to use?
When people post things like "M$ is nothing but a monopoly that should be shut down. I love my Mac." I just want to slap some sense into them.