In mailing list discussions I’ve seen Windows users get rather unhappy when people talk about “Hating Microsoft“, this often includes claims that it’s supposedly “unprofessional” to hate one vendor. Some go as far as to claim that it’s a good idea to avoid hiring someone who says that they Hate Microsoft – not that I would want to work for anyone who would reject someone’s CV based on a mailing list discussion.
The thing that they need to understand is that when someone says “I Hate Microsoft” it’s usually in a similar manner to someone saying “I Hate Broccoli“, it’s more of an expression of distaste than real hatred. The IHateMicrosoft.com site has animated pictures resembling nuclear explosions , which is good for a laugh (the site also lists some real reasons for avoiding MS). But there doesn’t seem to be any evidence of real hatred for MS, even in the US there doesn’t appear to be anyone wanting to use violence to solve the MS problem.
Abortion doctors are hated, MS isn’t.
The next thing that people need to know is that a significant portion of the “I Hate Microsoft” sentiment comes from people who spend about 40 hours a week being paid to use MS software. I am fortunate that it’s been a few years since I have had to use MS software in any way and many years since I was forced to use it in any serious way (IE anything other than using Windows as a SSH and email client), so I have little immediate need to get angry at them. But people who are forced to use or support MS software on a daily basis will often get unhappy about the situation.
It’s little things like an ActiveX bug that exposes Outlook and Internet Explorer to remote comprose  that can really annoy people, there was never a need for ActiveX and certainly never a need to have it work via email or be enabled by default. But MS released their software to work in that way and now all the users have to wait patiently for a fix (or scramble for a work-around).
Another issue that seems to get some complaints is the use of terms such as “M$” and “Microsloth” to refer to Microsoft. If that annoys you then please get a grip on yourself! It’s a software company not a religion! Official company documents should have all trademarks spelled correctly, but for casual discussion on a mailing list I think that such slang terms are appropriate. If nothing else you can take it as a declaration of possible bias.
I don’t use such terms, but again that may be because I am fortunate enough to not use MS software. When someone is unable to avoid using inferior software due to the anti-competitive actions of MS it is understandable that they may vent their frustration by misusing trademarked names.
Remember that English is a lot different from any language to use when programming computers. Using “M$” instead of “Microsoft” will not give a syntax error or an error about using an undeclared variable. The word “hate” has different meanings depending on context.