Read this review of the card.
I think you do not need any additional cable for the most basic TV watching/recording.
Just attach the cable from an amplified TV antenna or cable TV source into the CATV input of the card.
Although it supports High Definition, nonetheless it is 2005 technology and it just might not be too happy with the High Definition content of today's standard. This goes hardware wise and software wise.
On a brighter side, Pentium 4 at 3.6GHz should be able to handle this card, according to its spec.