Hy the question may look weird because one of the coolest thing in Linux is for install or update the SW with Synaptic (ubuntu) or the equivalents of the other distro
But this work well here in the EU or in US, but in other context will not work
As example i plan to go back in Africa were many more of what you may think have a computer but very few may pay for decent internet connection (last time i was here the price of 1 mounth 1MB connection was equivalent at 2 months rent of a 5 rooms house with hyuge garden and dependencies,

)
well to make the story short i plan to go back there at soon the situation will allow, and many of my friends have, often even good PC, all running Windows, and almost none of them may connect (if not from their Office, or occasionally from internet cafe)
It seems that i am the only linux users, also because install and update Linux without a connection seems a pain, while you may found here all windows programs on Cd or Dvd,for a few cents
So i will like do something to promote linux, for passion in most of cases, and in other to case gain respect and, why not, a few bucks (i saw businessmen doing delicate transitions from unecrypted wireless connection and unprotected computers,... the chief of the bank that i was using has her work PC protected by a 3 word password: her initials

)
I will have no problem to install dual boot even taking care of back up, but once installed i would be forced to explain how to keep the OS updated, and in many cases to provide DVD and how to
Note that i WILL HAVE a decent connection, so i may download and burn on dvd what needed , but for the how to i just have no a hint,( search gave me too results mostly seems written in a nerd only language )
But i suppose may be explained with simple words:
1 may access to the net and download what needed, how to help the other 99 with same OS that can't access to the net, to mantain everything updated ?