Re: Something like Arch Linux with no net?
I've installed Ubuntu over the net a number of times. Back in the days when I had to watch my data use fairly carefully, I basically set up a repository on a machine on my LAN and directed apt-get to that. There are various ways of doing that - apt-cacher-ng is one of them which also works for Debian.
Whether or not you can direct apt-get to a CD/DVD depends on how it is set up. If it's just a collection of packages, it won't work. It needs to have the repository control files so that apt-get knows what to do with it. But the packages can still be imported into apt-cacher-ng
I'm not sure what's available for non-deb distros. There's almost certainly a way of setting up a repo on your LAN. You wouldn't need a fancy machine for it, either.
Please, people, remember to BACKUP before you install that new system. Same if you're upgrading.