Monopolies arent illegal that I know of - only the abuse of those monopolies is illegal
Give me an example of how Microsoft have abused their position in the software market. I would have thought that if there's only one company able to market it's product well then that company will certainly do better than it's competitors. Don't get me wrong here, I'm not a Micro$oft advocate. They don't need me or any other unpaid user of their products to help them along in any way. But given that you pay for Windows and are able to get most, but not all, Linux distributions for nothing it must say something about the userfriendliness of the whole range of products. Grimz made a good point about Linux, it's okay for servers because a server just sits in a corner and gathers dust. Windows is a far better environment for the desktop or workstation. Why? because it is user-friendly. If you talk about domination then look at all the freeware you can get for Linux and then discover that it has specifically been made to be as compatible as possible with things like Micro$oft Office. This of course is a perfectly reasonable course of action.
Back to mIRC - you got your answer on that before you even uttered a word, I'm not going to bother repeating it. Also, if you want to get technical about the meaning of the word monopoly then you'd realise that it doesn't apply to Micro$oft anymore than it does to any other large company or company with a large market share. "Mono" is a Greek word meaning one or single. Source: Macquarie Dictionary. So I can safely assume that by using the term monopoly you are referring to a company with a large market share, not a company with 100% of the market share.