Use a multi drive NAS such as WD or Synology and host the files there for video and audio. This will give you redundancy so you don't loose data. Host the Plex server on your Vista PC or get one of the Synology models or equiv that can directly host the Plex server. Use Roku 3 for local playback.

I have a customer with the 4 drive x 4TB WD NAS and a basic Slim Acer i3 computer used for ripping and hosting the Plex server. This was to replace 2 Escient units with 6 400 disc DVD changers that were all full. Full setup is less than 2k.