Hi Merlyn,
A SNAP server is basically a small external fileserver, right?
In that case I think what you are looking for is a product called Samba. You can find info on that by searching google or on this site I'm sure.
Samba is a software package that installs on your linux box that allows it to act as a fileserver. You can share certain filesystems or directories on it and other machines on your network can access them as if they were local.
There is kinda a lot to it, but by pointing you in the right direction I'm pretty sure you'll be able to figure it out. Check out the website
http://us4.samba.org/samba/ to get started.
As far as which linux you install it on, there are plenty of good choices. There are tons of threads on this site which discuss it so I won't rehash them all here. Use the search and you'll find way more tips than I could give you on which version to use.
Good luck with your file server project.