Not many folks really "hate microsoft" and many who hear that will say "oh you're just jealous because they are successful!"
Microsoft got where it is today mainly by gobbling up smaller companies and squelching competition. They're a huge mega corporation and many consider Bill Gates to be a geek rich boy. ; )
Many folks feel that MS pushes often inferior, buggy, bloated, overpriced products on them, soley because of their marketing muscle, while crushing potentially better/cheaper/faster solutions that would more greatly benefit consumers. These folks get sick of seeing Microsoft's big name on everything computer related.
Other folks have more practical reasons, such as they feel Microsoft is a monopoly, and therefore illegally destroying competition in our market economy. Others feel that microsoft's products are not often the best, and this is partially because they don't have to worry about competition, they just buy up or run the other guy's often equal or superior product out of business.
Now everybody's got an opinion on this issue, so let's not start a big flame war about it.
Personally, I use alot of MS-related products, and most of it is because of convenience. I don't go out of my way to buy them or support them, I just tend to use them. I know where to find the alternatives and how to use them, so I'm not wholly dependant on them for anything.
That doesn't mean I think they are the best or only ones out there though. Feel free to use what you want I say, and let the other guy make his product if he wants to.
The consumers should have their free choice of what to spend their hard earned money on.