Question: I want to set up a source code control system that:

1. is networked, so users can access it at work or on the road
2. does not need to provide sharing, lock mode is sufficient
3. there will be only three users and they will never be working with the same code
4. we have no system administrator and not much knowledge in that area so the set up and config must be dead simple.
5. will be installed on a Windows server
6. open source or free

Suggestions please.

Answer: 
[SVN](http://subversion.tigris.org/) covers all of these, and is quite easy to set up.

Wrt point 2, sharing tends to be better than locking, as a file that is locked by someone who then goes on holiday/dies/etc. needs to be unlocked by someone before it can be worked on by another developer. SVN supports sharing 'out of the box'.
I recommend [Tortoise SVN](https://tortoisesvn.net/). SVN is a source control environment that's easy to set up and use on Windows, and Tortoise is an add on that integrates with windows explorer.

Despite being simple to use, it allows different people to work on the same file and merge their changes. Even though that "can't happen" I predict at some point you'll be happy that it works that way.