A Sony TV tuner is discussed in the following thread, read down a bit for jeo4long’s post.
http://www.siliconpopculture.com/sonytr/viewtopic.php?t=396&highlight=tuner
Otherwise, you can pick up a USB tuner, but not many come with an antenna, so you’ll need a coaxial input to get a signal. I use an ATI USB TV Wonder to watch shows occasionally, but all the extra wiring and bulk is a pain, so I record shows on another machine and stream them wirelessly to the TR.