Remember, the iPod touch, iPhone, iPod classic, and iPod nano 3G will NOT work on any cable that does not have an Apple authentication chip in it. So you basically have to buy Apple's cables.
Component will look better but more TVs have composite connections. If you plan on using it on a lot of different TVs then you might better off with the composite cables.
The iPod classic and iPod nano are capable of 480p output.