I think that I can answer this. I also have a lcd with dual Qam (digital) and analog tuner, yet only one coax input. If i put an antenna I receive 20+ Digital channels ( 8 hd) but no CBS (chicago land signal issue). If i plug into my wall with basic cable and NO box, i receive 78 analoge channels plus all of the local hd and digital channels (including cbs, channels 100+) since Comcast relays the locals over the wire.
Now if i wanted to record or watch both in LMCE 'PVR i'd need a winttv 150 for the first 78 channels plus a digital tuner such as hd homerun to allow for recording and distributed viewing in other rooms. The hdhomerun which is a dual qam that would allow dual digital or hd recordings or viewings at the same time. I'd need two winttv 150's or 1 wintv 500 to get that dual capability for the analog channels. The hdhomerun also would alow for an antenna to receive the over the air digital and hd local's as an alternative to a local cable company relaying the local's
Now either the hdhome run or the wintv's input can be "split" and ran directly to my LCD for viewing, but that wouldn't allow for recording or distributing with out the appropriate analog or digital tuners or both tuners. Happauge does make a 1600 series tuner that is a dual analoge and digital (qaM ) in one card , but not yet supported in linux. if it was supported it wouldn't allow dual recording or recording and watching of 2 analog or 2 digital channel similtaniously, you'd need two 1600's for that, but the one 1600 will allow for a distributed watch or record of both 1 analog and one digital channel at the same time.
hope that helps. Shaun