I don't see the point of trying to use a PC for this. All you are doing is making the PC work as a very expensive and software based distribution amp. Just buy a hardware box to do that and leave it be.
Of course there is another way to do this.
You could use MediaPortal (
http://www.team-mediaportal.com) with the DVB-T and DVB-S cards in your PC to act as a TV server, recording and streaming the live tv to multiple TV client PCs hooked to your TVs in different rooms.
This is what I have. Right now there is just a single Dual Tuner card in the TV server, but I'll be adding a second once I get round to shutting the box down. And eventaully I'll add a couple of DVB-S feeds too. Then I have PCs connected to TVs in the bedroom, living room and kitchen that receice the centralised EPG, recorded TV archive and request live streams from the server.
It's not perfect, but the software is improving all the time. I don't have the kitchen system yet, but I think I'll get an Ion based nettop to power a 24" monitor.