An HDMI would simply run both audio and video through one cable. That is the main advantage of the HDMI over component. There is a little difference in over all picture quality in favor of HDMI, but that is strictly my opinion. See for yourself though, ask around to some friends that may have a set you could borrow. You could easily pick an HDMI up at walmart or target for around 10-15 dollars and an actual vizio brand for around 27 dollars. Monster cables are not necessary, don't believe the hype.
Okay...So I just purchased a 32" Vizio HD tv (it has the HDMI ports). I already have an Xbox 360 (arcade) but I have the component cable that has the little switch on it that switches from TV to HD. My question is, do I need to buy an HDMI cable? How much of a difference does it make? I don't actually have the tv yet because I ordered it online, but I would like to know if I need to buy an HDMI cable. I read on some other threads that if I have a sound system it would be smart to get the HDMI cable, but I would just play the sound through the tv speakers. Any advice would help a lot!!
Thanks

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic