Why does everyone want to make fun of poor Bill? I have a windows/linux dual boot and a Mac and quite frankly Windows is okay. The truth of the matter is there is an operating system right for everyone, Windows is right for most people:
Windows is packed full of "idiot" guides. Hell they even have a desktop cleanup wizard! They have the annoying paperclip that likes letters, it automatically does stuff so you don't have to. The problem with that is that the bigger code you have the more chances for unfixed bugs. You constanly get annoying alerts, you constanly go through wizards to do everything. Which is helpful for people that don't know shit about their boxes. However when you are more experinced you want control of your box. 70 % of people use it so pretty much all viruses or malware is written for it.
Macs are for the people that knows about computers but arn't geeks that are on them constantly. They have less chances for viruses and don't have that many idiot guides. Therefore it is less buggy.
Linux is for the geek that is on his computer 10 hours a day programming, surfing, ect. He knows alot about computers and doesn't need idiot guides. He does everything manually. There is a real low chance for bugs and you control your computer (not the software). It is really small and can fit on almost everything. There are hundreds of distros so you can pick the one write for you!
BeOs Similar to linux. I have never installed it (only used it at a friend's house) so I can't talk much about it
Sun OS I hate it and hope it dies (it already did)