Microsoft are well known for stamping on anybody they think may be a threat to them, which has, sadly, probably led to the demise of many upcoming companies that may have made a useful contribution to the development of computer systems in general.
Even in the early days some of microsofts ways of operation where dubious to say the least, the original DOS was largely based on a CP/M operating system and strangely had many features of a UNIX OS, the entire idea for a GUI never anything to do with microsoft (or apple) but was pioneered by xerox (think they may have even copied the idea from an earlier concept by some guy at an American UNI) and the windows based OS's we all know today was then copied by, Steve Jobs and Bill Gates.
I agree with AC that some of the worst things MS have done is trying to make their OS be as non-compatible with other peoples software as possible, in doing this they have probably, again, held back useful development by years.
I do use Windows on a couple of my computers, both laptops, though this is largely due to having to have a compatible system for site visits, I am currently on a Linux system (MEPIS) and find it as easy to use on a day to day basis as a windows system, and it is very very rare that I have to drop back to a shell to do anything which is probably what puts most people off linux. I also administer several servers which are all Linux based and for a server environment i would not even consider using windows (unless there was a really good reason, such as a server based package that really needed a MS server)
If anyone is unsure about Linux I would say give it a go, there are several Linux distros that can be run from the CD and will give you the chance to look before you leap
Mark