Basically, no ... All you should need is access to 'online' storage. Support for UPnP, DAAP, NFS, Samba or any other media protocol/drive mounting protocol should be standard. You should not need a hub (PC in this case) bridging the content to the streamer, especially if the content is not even hosted on the computer.
In my case, I only want to have my low wattage consumption NAS running and leave my PC alone. Presently, I have a DAAP server running on it and have NFS and Samba 'mounting' available and I am able to stream all my content to my devices, things should evolve in that direction without other dingles to run.
Roku HD1000 (revived!), R1000 x2, M1001 x2
Linksys NSLU2 with Firefly
Netgear WGR614,JGS516,GS608,GS605 x3