Is HDMI noticeable as in you can see the difference compared to normal 3 way cords

There is some difference but unless you were in the A/V club at school, it's hard to tell.

HDMI carries the audio, as well. So it's less messy and all digital to the TV. Component is not.

Shop around if buying HDMI cables. Most stores charge way too much. Having "Gold Connectors" really isn't worth the price.