I installed linux on my mum's computer, and it is much easier for her to use than windows. She doesnt need to know how to install software on it, all the software she ever needs came with the distro when she clicked 'Next' during the installation. She doesnt need to know how to recompile the kernel, all her software and hardware work properly already.
When my mum was running windows, she would get confused and call me every time a warning message came up, and when I went to her house one day her computer was infected with so many trojans, viruses and spyware programs that she couldnt even use her computer any more. That doesnt happen in linux, and everything is easy for her. She wants to browse the internet, fine, she just clicks the Firefox icon on the toolbar. She wants to check her email, she clicks the Thunderbird icon. She wants to write a letter, she clicks the OpenOffice icon. Simple.
People that use windows seem to be under the impression that it is perfectly ok for an operating system to be unstable and insecure, and to need to reinstall it every 6 months and restart it every few days to keep the system from grinding to a halt. It is not ok. And to have to pay hundreds of dollars to get Windows with some decent programs like Photoshop and Office is unaceptable. I can get Linux with GIMP and OpenOffice for free, and it may not be as good, but it does the job and saves thousands of dollars when decking out a small number of computers.
When i try to convince people to use linux, they say 'Why fix what aint broke' or something to that effect. Well windows IS broke, people are just ignorant to it. I agree linux may not yet suit the needs of many people, but look at how fast linux is developing. The number of GUIs being made for command line programs in linux is skyrocketing, and it wont be long until every common program has a decent GUI, and Windows users can stop complaining about having to use a command line in linux.