It matters what TV card you are using!
I'm using ATI TV Wonder VE. I'ts not bad but it has mono sound and it fits in a PCI slot.
Good fast ones fit in your AGP expansion slot as a video card/TV card and could have 128bit graphics capeabilities.
Some cards also have HDTV but is very expencive!
Also I only have 1.4Gig P4 and I find that if I record from cable; -I can't have anything else big running otherwise I will miss more frames in the tv program that I'm recording.
You might get a good card off of ebay that is a year old and works very well for an affordable price?
Later