Subsonic (
http://www.subsonic.org/pages/index.jsp) is another alternative media streamer, that only does music, that I use. Its a little less user friendly than Plex (which I also use) but I feel like its more reliable (Plex can be a little buggy)
PC, unfortunately when you buy (rather than build) a NAS, you'd running on a smaller more proprietary operating system than if you had network storage on a regular computer, on your network. So that limits what your going to be able to do with it. My setup, for example, is just a spare computer with a RAID array connected, that also serves as my HTPC. If you want to link the product that is running your NAS, I could probably come up with a snarky LMGTFU link that would get you pointed in the right direction.