I ran into this exact issue recently as I introduced SVN to the entire web dev team (consisting of programmers, interface builders, graphic designers, content editors, site moderators, and non-technical managers). I looked around for non-technical documents but ended up with very little that was usable so I decided to build my own. Unfortunately the majority of info out there expects users to know about client/server architecture and what a 'branch' is - I could not assume that in my case. You can view one of my pre-migration PowerPoints over at SlideShare ("What Is This Thing Called SVN? FTW or WTF?")
http://www.slideshare.net/secret/wBsLzZb3O7cXCU
The real key was to explain that SVN - at its heart - is really just a better way to approach copying and pasting files. Getting rid of default.bak, default2.asp, defaultBackup.asp, defaultMyCopy.asp, etc... was something that everybody could understand.
As my users became more familiar with the idea of source control I encouraged people to ask questions on our internal WIKI so that the dev team (and other users) could help them out.
We also built a custom SVN desktop tool to auto-set up their local desktop in a consistent way so that everybody across the company was guaranteed to have the same setup as everyody else (c:\projects\projectname) and it also updated their local IIS installation so that they could view websites locally at any time without needing to configure anything by hand.
So - provide lots of hand-holding - use some humour - make things simple - keep it standardized - provide a way to ask questions - provide support - identify with your users and their need to "get on with their day". And if possible, sit at their desk and walk them through the process as many times as is necessary to get each person over the hurdle.