I used ArgusTV for a long time. It's a royal pain to get setup, and you still have to have something to use as a front end to actually organize and play stuff (I used XBMC). There is an external tool (I've totally blanked on the name) that will rename the recordings to XBMC standard Series.SxxExx.Title.ts, and I think that would work with Plex too.
ArgusTV just crapped out on me one day though and wouldn't recognize any of my tuners anymore, so I switched to NextPVR. NextPVR is easier to setup, but the documentation is only marginally better. There is an external tool for that called ImageGrabLite that will rename stuff to the XBMC standard. I've never used the front end of it, as I still use XBMC for that.