Hi there If setting up an HTPC then would suggest you take a look at the links below for starters. have you thought about what front end you want to use, Emby, Kodi, Mediaportal or J River?. click here (Would start by reading this 1st) click here (this is my software of choice) click here lot should give you a good starting point of what to look for and how to set up, Are you going to use a Freeview TV card or a Freesat TV card or both? for TV cards the best are probably the Blackgold ones but can be a bit expensive.
If you have any more questions just ask.