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: 
the *SIMPLEST* system is what we here call the "Hey Chris" system. We have a networked drive that everyone can mount, and if you want to edit something you shoud "Hey, Chris, are you working on blahblah.cpp?" and Chris says "Nope." and then you edit blahblah.cpp, and stick it back on the shared drive... If you want versions, just back up the networked drive every night. 

I never said it was the BEST system, just the simplest.
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.