So I have always gotten jokes. A friend told me his favorite and i just don't understand it. I did a web search and found variants but no explanation why it's funny or what it means. Can you help?

It was nothing to do with Windows, it's a sorta joke where the person telling the joke is trying to use logic to compare 2 different things, with humorous results.

A better example is an old Norm Mcdonald (I think) joke, I'll post it below.

A guy sees his new neighbor out in his backyard, so he decides to get acquainted. After introductions, he asks the new neighbor what he does for a living.

The new neighbor says, "I'm a professor." The first neighbor then asks, "Oh yeah, what do you teach?"

"Logic," the professor reponds.

"What is that?" the neighbor inquires.

"Well, let me see if I can give you an example...you have a dog, right?"

"Yeah, that's right," neighbor #1 responds.

"And you have children too, right?" says the professor.

"Wow, right again!" exclaims the neighbor.

"So, then you must be married and that would make you a heterosexual, right?'' proclaims the professor.

"Unbelievable, you're absolutely correct. How do you know all this about me?"

"Well," the professor says, "I observed there was a dog house in your backyard, so you must have a dog. I also saw bicycles next to your garage, so you must have children. And if you have children, you are probably married and if your married, you are most likely heterosexual... it was all logical!"

The next afternoon, the neighbor runs into his old friend. His friend asks if he has met the new neighbor. The man says that he met him yesterday.

"What's he like?"

"Well," the man says, "he's nice and he is a professor of logic."

"Oh," says the friend, "what's logic?"

"Maybe I can give you an example. Do you have a dog house?"

"Why, no, I do not," responds the friend.

"Well, then," proclaims the man, "that means you're gay!"