Component Video cables vs HDMI

Thanks everyone for the excellent replies. Appreciate it.

HDMI will improve the picture quality. Saw it for my own eyes when I first acquired a bluray player and went from analog to digital interconnects. A test was to pause the disc and flip between inputs on the television. Close-Ups with hair in the shot really showed a difference in detail

On use as a cable box signal transmitter Comp video is fine as nothing is 1080P, some may have SELECT PPV movies in 1080p but if any at all it will just be a few. There are increasing attempts to pass off a upsampled 1080p as a game changer, its a con.
I have actually seen better results when going Comp video over HDMI, it may come down to length and quality of cable all told. But on the average size home display wich is usually less than 50in your not likely to resolve any change in detail, pixels are simply too small. On projectors and monitors around 60in you may be able to but I still doubt it. HDMI is a simple route to go just DONT go to RadioShak, Bestbuy or retail for cables, Partsexpress.com and others listed above sell good cables at good prices.
But just like in audio if you want to see a improvement you will talk yourself into it, such is life.