You can inform yourself.Search for DRDOS.Search for windows trademark issues,lindows, you know what? they were an entire line of windows branded products before MS, MS destroyed them all, you can search what happened to them.
Windows is a generic word, it can't never be trademarked(unless you are rich to get over the law), that applies to "word", "powerpoint", "project", "excel", "exchange". A word in the English dictionary just can't be trademarked, by law.
Maybe you were a kid then, but there was a time when "word" was not the most used word processor, it was "WordPerfect", and people used Lotus123 instead of "excel". What did MS did? They made windows but didn't let WordPerfect and Lotus123 people(and everybody else, like compiler builders) use the windows API, so MS had a 4 year period of advantage. Once they did, the high level exposed API was slower than what MS used.
I'm tired too. When people don't know they don't know what they don't know.