HDMI cable made a difference in picture quality??


I just bought an a 42 inch LG LCD flat screen TV which is has full HD function. I have a HD cable box and opted to use RCA cables betwwen the box and TV. I am getting missed opinions from the cable provider and the LG dealer about the usefulness of the HDMI cable hookup. Does it actually improve picture quality??? If so,how much? and will it also improve non-HD programming??? I have seen several adds from Monster Cable and Audioquest touting their HDMI cables. Monster has one that is about $70; another is about $100. I have seen even higher price tags from Audioquest. All comments welcomed. Thanks Jim
sunnyjim
I am getting missed opinions from the cable provider and the LG dealer about the usefulness of the HDMI cable hookup. Does it actually improve picture quality???

Some people and members of this site will say that using HDMI improved the picture quality and some will say that they saw no difference . Try both ways for a few days and see which way you like best.

and will it also improve non-HD programming???

Meaning the digital channels or the analog channels ?
HDMI cables were designed to transmit digital signals, both audio and video. I would use HDMI cable if you want to take advantage of your 1080p TV. HDMI cable does make a difference especially if you have bigger TV.

I compared a generic brand ($45) to a Monster Cable Ultra 1000 ($120). The Monster is better in sharpness and color saturation. Lately I switched to Kimber Cable's HD29 which is slightly better than the Monster but costs more.
I tried both connections and really did see a marked improvement with the HDMI connection on my 50" plasma. You can get very high quality HDMI cables from Firefold or Monoprice for very little cost.

I actually A/Bed the $7.00 Firefold HDMI cable to a $100 Monster Cable HDMI and preferred the Firefold.