In short, basically nothing will work like you want. For satellite you are pretty much limited to s-video capture, or if you are really lucky, firewire (no card needed). For the short term, you can pick up a PVR-150/250/500, but after Feb 2009 it's only use will be for s-video capture. For grabbing stuff off cable, the HD Homerun is your best option, depending on what the cable company encrypts, but you already said you don't want it.
Hopefully in the future the HD PVR will be supported, but that's just HD component capture (requires HD component output from a cable/sat box) and is currently $250.
Encryption, conversion to digital cable, and lack of drivers has Linux a bit lacking for options. Your best bet is to hope for a "good" cable provider in your area and HD Homerun.
BTW, next time wait more than 4 hours before complaining about lack of a response. You're topic likely had a bunch of people curious, thinking perhaps you provided useful info on a few different options, hence the 17 views.