Hi,
I have also been wrestling with getting my new Hauppauge PVR-150 MCE TV card to work with LMCE. I was getting an error in Mythtv every time saying that all available inputs were being used by Mythtv. After four days of trying different options, reading every related post I could find in the forum, reinstalling LMCE several times, and even trying out Knoppmyth, I finally found how to make it work.
I had everything else in the UI more or less working as it should. It turns out that the Mythtv setup in LMCE does not work out of the box with the PVR-150. You need to do the following:
1. Start Mythtv Setup under the Computing option of the LMCE UI.
2. Go to Capture Cards, Add new card. Mythtv can see that there is a PVR-150 card available. Change the V4L option to MPEG-2. You should now see there is a new entry on the list for your PVR-150.
3. Go to Sources and add a new source for your cable provider. You should see the new entry on the list of sources.
4. Go to Connections. You now select Tuner1 and specify this tuner is connected to the source you just created. Tell the setup program to scan for channels.
Thats it. Exit setup and now the Mythtv "Watch TV" option should work.
Best of luck,
Jaime