I have a Hauppauge pvr150 card running on my box, and I get tv by:
open VLC player
sudo apt-get install ivtv-utils
File -> Open Capture Device -> PVR -> OK
then you can do (in terminal)
(25 is channel number)
which changes the channel.
to see the options which control the card.
for a cool desktop tv remote,(so you dont have to use terminal to change channels) go to: http://tvremote.sourceforge.net/
remember to have java installed first. then you can right click: open with java.
to record tv:
it will record whatever channel you are on. then ctrl-c to stop.
cat /dev/video0 > /tmp/name_of_file.mpg
but i have cable tv, not over there air. but it should work.