Joe Stewart is the director of malware research at SecureWorks, and presented a dire view of the current botnet landscape at the RSA conference this week. He conducted a survey of the top spamming 'nets, extrapolating their size from the volume of emails that flow across the internet. By his calculations, the top 11 networks control just over a million machines, hitting inboxes with some 100 billion messages a day.
There are at least 1 million people out there who probably concider themselves average computer users, but don't have a clue what they are doing.
Getting by and using a computer properly are two very different things. I mom's mother gets by. She does what she wants, for the most part her computer is fine. Every now and then something blows up. But she does not run windows updates, ever, she installs anything that meets her fancy at the time, and she buys software without reading requirements. The last time I used her computer it was because she was getting virtual memory errors. The amount of crap running and installed blows my mind. She had 3 weather programs!
So I guess you must define a regular or normal user. If that person knows how to install software there is no reason they would be confused by linux. Installing windows software is a task:
1) go to a store or search on the internet to find software
2) READ system requirements and make sure you meet them
3) download/buy software
4) Run setup.exe. setup.msi, install.exe, install.msi, autoplay.exe, etc, maybe just put the cd in, maybe not, you get the picture
5) click though (and god I hope actually read) all the screens of the random multitudes of installers out there (ok, there is probably 4 or 5 I can think off ). In some cases this is where you will get asked questions that seem very dangerous (Do you want to install directX 9c?) I hope you know what that means. Some cases you will get prompted for missing dependancies and the installer will fail (you must have .NET 3.0 to contiune).
6) Now you are done, enjoy your software.
That took some learning for the regular user to do. It is not intuitive. Now lets look at ubuntu.
1) fire up add/remove software
2) search for the application type you are looking for
3) click the recommended program
4) tell it to install
5) read and accept the license
6) sit back and wait
7) Now you are ready to use your software
or if you need more choice, fire up synaptic and search that. Ubuntu will handle any dependencies and in 99.9% of the cases you already meet teh system requirements out of the very basic nature of being able to use linux.
Mac is mostly easier then that, I just hope to god you don't want to cleanly uninstall anything. However you are still faced with a problem with mac, finding software and making sure you meet the requirements. This means searching stores and the internet for the apps you want.
So if we are going to say an regular user can go to best buy, find and install software, then there is no reason to claim an average user can not install software on ubuntu.