Ok, here...
TV Tuners
http://www.ascent.co.nz/Category.aspx?majorcatID=97
More TV Tuners
http://www.trademe.co.nz/Browse/SearchResults.aspx?searchType=0002-&searchString=TV+tuner&type=Search
68,000,000 hits for "how do I watch TV on my PC"
http://www.google.co.nz/search?q=how+do+I+watch+TV+on+my+PC&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a