CB,
This post reminds me of the initial struggles I had to get the MC network up and running about one year ago; the settings seemed pretty clear only after I'd figured out how to enable a number of options (i.e. Self-Evident in Hindsight.)
It looks like you have the server/client system up and running, but make sure "Authentication" is checked on all computers, not just the main library server. Then, click "Automatically sync changes..." on all computers under Media Network/Client Options. This ensures changes made to the client libraries are also made on the library server.
Also, make sure Startup/Media Server is enabled on the server computer so that it runs constantly.
In addition, one nice feature I have up and running on a similar home network is Wake-on-LAN on my server computer. My client computers automatically connect to the main library and wake the computer from sleep or even turn the server on cold. You have to enable this through the Win7 OS, and then client computers automatically send the WOL magic packet to the server computer. I like this because I don't have to run the server all the time, it's a laptop and not really designed for constant use. An upgrade to a dedicated server with bigger storage capabilities is on my short list.
It is interesting to note that I purchased MC and joined Interact one year ago; ALL of MC's networking features have been continually tweaked and improved over this time...we've seen nice updates to Gizmo as well. Big thanks to JimH, Matt and co for the work in this arena. The wiki may be out of date because of the quick pace of change over MC15 and MC16.