I would agree with plex (or something similar) just for organizational reasons.
Yes would take a little initial setup..
But overall in general, to find stuff would be easier quite possibly.
(EG: If you have a MOVIES folder on drive A.. its full, now you have one on B, etc.. which drive was witch on, etc?)
Sure you can use something simple like DLNA.. but again comes down to where stuff it.
Something like Plex, will give you a nice front end interface, pulling from MULTIPLE sources for one category.
(there are other options like XMBC as well.. it has more 'channel' options I think for other sources.. but for the MEDIA setup/cataloging portion.. I found it took much longer to tweek it)
As for the hardware.
If you are going to use all the external drives (and not consolidate to a NAS, etc).
You don't want to get something TOO basic.. but you don't need to go overboard either.
Depending on your playback devices, they may need transcoding or not.. transcoding takes stress off the end device and it doesn't have to do any decoding.. but it makes the 'server' work and do it. So don't want to get TOO simple.
As for connecting the drives.
I forget who said it on the previous page (exdilbert?) but I 100% agree on getting USB cards for the PC (ontop of whatever ports are built in), and to NOT go with hubs.
Even with USB 3.0 hubs.. you are creating a more potential bottleneck with filtering through... if one person is drawing off dive A and another file off of B through the same hub.. MIGHT experience some issues.
Better of to shorten the path, remove as much bottleneck situations as possible.
(my current setup, desktop PC, with 2x 2tb drives in them for media. Each of them has the same folder structure.. so some movies could be on both drives.. but plex just points to the two folders for one category. I DO have usb drives attached.. but I do not use them for media serving.. so cant comment on their quality for doing so. Mine are used solely for BACKUP/Duplication of the media drives.)
Rogers Ignite Xi6, LG 47LV5400 LED TV, Yamaha