The cable that comes with the TiVo seems fairly high quality to me.
I wouldn't exactly go that far but I will say that it is adequate for most people. Personally, I prefer something a little more robust than the cables supplied with the HDTivo, but that's just me.
The OEM cables that are included with most consumer electronics are generally crap, particularly audio and composite video cables. The first thing I do is toss most of them in a box and replace them with better quality cables and connectors.
Rather than risk a long drawn out debate on the topic I will say that you can get some inexpensive but decent quality cables from monoprice.com. I don't condone the ridiculously overpriced esoteric cable industry. They're really designed for those that have more money than good sense. Monster cables are a joke and nothing but hype IMHO, not to mention priced way beyond the performance value they claim to provide.