There’s a story on slashdot.org about the software I’ve been using on my ‘tivo’ computer, Beyond TV. I’ve been very happy with it despite some occasional glitches and the thread is well worth a look if you’ve been considering setting up your own personal video recording box.
One word of advice that only a few folks mention in the thread – if you’re serious about doing it, invest in an MPEG encoding card for the machine you’ll be using. The difference in quality is night and day.