Perhaps look into AnySee Netstream N7 HDTV. No need to put the hardware in the pc, just a little box that connects to your network and you can stream tv channels from that with VLC player for instance.
I'm still searching for a usb pen capable to sync Portuguese digital terrestrial tv, but it's hard to find anything with stock/decent price/ working with Mpeg4 :|
ill get it one day
so the quality depends on what the cable company provides.
Got it in my laptop for 2 years already.