Mac has its purpose. Believe it or not, there are a great many stupid people who have no clue how to use a computer properly. Mac is great for them with its hold-your-hand design, one company to call to fix service, and limited confusion with just 1 button to worry about on the mouse. Installing software doesnt require any brains at all.. just drag the program where its supposed to be, just dont drag it into the trash unintentionally.
PC Manufacturers today throw too much of their own crap pre-packaged onto the computers, and since nobody who buys them and doesnt know how to use it even thinks of getting a manual for it, they are hopelessly lost. Then they start clicking all those shiny banners to install software, which runs on Windows, they open those emails about winning $1,000,000, and before they know it they themselves have completely screwed up their computer by their own doing.
Most computer problems today are not caused by crappy OSes... to each his own in that department, but most problems are caused by user error. Personally I am a Windows user. I built my own PC and it runs Vista. I am happy with it. I also own an OSX Tiger computer and hate it.