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: 
Try [Subversion (svn)](http://subversion.tigris.org/).

Edit: Rich beat me to it =D. And yes, as he points out sharing is better than locking. Sounds like you're a SourceSafe user. Those were the same set of problems I was trying to address when moving out from SourceSafe =)
[Darcs](http://darcs.net) provides all this and a lot more. It's a distributed version contoll system, which would make it easier to access the data on the road. You can send/receive patches (similar to revisions) through email or ssh.

The thing about darcs that I like the most is that it's really verbose. It really tries to help you.