I just setup the cable card tuner last week so I'm still learning quite a bit. I originally thought it would never suffice as my full time living room DVR.
The combination of MediaBrowser and MCE buddy are quickly changing my mind. I'm still using my Fios DVR for the time being. I'll probably make the full time switch after I order a HDHomeRun, giving me 5 tuners 3 of them being dynamic and network accessible from my varios HTPC's for live TV.
@jjwrest - What TV Tuner card you get is going to depend on what cable subscription you have. If all you have is a basic cable subscription (no cable set top box required), then any of the basic tuners, like the Hauppauge PCTV HD Stick 801e SE USB 2.0 would work for you.
If your cable subscription requires the use of a set top box, then you could use a TV Tuner, like the one linked above, for standard definition recordings or you could replace your set top box with a CableCard TV Tuner; either a networked tuner like bjaminnyc has or an internal card like I have; the Ceton InfiniTV4.