From personal experience (I used to sell TV's and home audio stuff and still routinely hang out with my former coworkers who still work there), there won't be a huge difference between component and HDMI. Between composite (the red, white, & yellow cables) and component there is a huge difference. Size wise, for clarity and the whatnot between 720 & 1080, somewhere between 32" & 40" it becomes noticeable depending on the source and what you're used to seeing. The crazy thing is the digital cables, IME, have no real lag issues if they're under 3 Meters. The thing that gets most people is that if you're in to video games, everything that's not Plasma lags like a mothers. LCD is horrendous unless you've put out top dollar. The LED back lit stuff isn't atrocious, but there is noticeable lag, especially in something like, say, Gears or Halo online...