Windows 7 install (recently) from disk is dead simple, please give an example of something you could destroy through fat-fingering. Anti-virus is pointless for most users who don't pirate software and who use a modern browser (along with some common sense... Like say, not installing viruses). Kiss it all goodbye is ridiculous, when was the last time you heard of a virus doing anything other than installing spyware or a botnet?
Most people pay your so-called tax because there is no viable alternative, these aren't the kind of people who will buy the parts and put it together themselves.
Finally, I found ubuntu to be more difficult to install than windows. Think "proprietary" drivers... And there are a bunch of fat fingering opportunities in the ncurses version of the install.