Very generally speaking, the 5 video cables you have (called component video cables) will provide just as good an audio and video feed to your television as a single HDMI cable will. Audiologists and videographers could argue for hours over the minutia, but for us regular folk, I believe the two are of equal quality.

Don’t worry about the quality of the HDMI cable. While expensive cables in general are a waste of money, digital cables like HDMI are especially simple – they work or they don’t.

Why You Should Never Pay More Than $10 For HDMI Cables

I would go with HDMI. And buy the cheapest one you can since digital is digital. All the gold plated connector – monster cable shit is marketing. It is a one or zero. It works or it doesn’t.

http://www.monoprice.com/ is very good and cheap. I six dollar cable there will cost 40 at BestBuy.

I can also recommend monoprice, I am very happy with cables I bought from them.

And back to the original question – they both work fine but I think HDMI is better because one cable is a lot easier to handle than five.

Here’s a quick comparison:
HDMI Vs. Component

Note that although HDMI supports 1080p and component does not, that is not a big deal, your Comcast box is not 1080p.

Firstly, handling is no issue, for they will be at a resting state behind the television. Also, are the high definition channels 1080p?

US cable and broadcast HDTV is not 1080p. Sometimes it’s 1080i, but I think it’s mostly 720p.

I think the only 1080p sources for consumers are Blu-Ray discs and some satellite TV.

If both your comcast box and your TV have HDMI use that.
The component cables can’t deliver a better audio signal, and from a cable box the component video won’t be fabulous anyway. So replace the clutter of five cables with one why not?