Hi flank,
Thanks for the note, and the encouragement.
After lots of futzing and cussing, I finally got pfsense to work on my old machine and successfully attached a wireless router set as an access point. I plan to let it run for a week or so to make sure it's stable, and then attempt to get a VPN client to work on it. That's a weekend exercise – and one I have to get right so I don't take my VPN-ready wireless router out of service too long. Hopefully it's not too complicated to set up pfSense to do the VPN tunnel.
This has been a HUGE learning experience. I knew practically nothing about networking (and still don't to be honest) but it's pretty fascinating to tinker with this. And also a bit frustrating at times :)
The media server project is on hold for later. That's way too complicated, if even possible, to set it up on the same machine along with pfsense.
Thanks again!