Why not set up something like Xerver
on each PC the files are located on (non-GUI mode is light as a feather), and disable access to the port you run it on in your router so it won't be accessible from the internet?
This is how I share a lot of stuff with my daughter.
She can just visit page hosted on my PC and take what she wants or needs.
Don't let the fact it's Java based deter you with thoughts that it will be all slow and bloated.
I have been using it for a long time, and even on my old 233mhz, 64mb ram Win9x machine, in non-GUI mode, I can't even tell it's running unless someone hits me up for a file. Even then, the only reason I know is because I can hear the disk activity (old noisy hd) and I take a hit on the available bandwidth on the 33.6k dialup it's using. But while it does lag the internet connection it doesn't lag my system at all.
Since you would be using it behind a router and not on the internet with really slow dialup, it's not too likely you'd take the same kind of bandwidth hit that I do on that machine. I certainly don't on the machines I have running it and connected to the router.