SageTV should do what you want. With their PlaceShifter you can also watch (ala SlingBox) your video from anywhere with a net connection.

The newest version of SageTV is adding support for DVB-S cards to compliment the support they've already added for DVB-T.

The only part I'm not positive about is the ease of changing your recording schedules over the net. Just skim their documentation and forum for the answer though.

http://sagetv.com

It's still the best PC-based PVR software I kinow of.