120 Hz is most noticeable on an LCD display that can have a lot of blurring and feathering in fast action sequences. While using simple algorithms for showing 24fps (at 72Hz it's 3x and at 120 Hz, it's 5x), will give you a marginally crisper picture for plasma, personally, if I had a great 1080p plasma, I'd hold off for a generation or two and see what other features I could get unless I had money to burn. Just make sure you're using a good HDMI cable so you're getting the best 1080p picture.

This is just my opinion from what I've seen.

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Actually, I've had two cases where a cheap HDMI cable failed for apparently no reason after several months or a year of use. See my blog: http://homeelectronicssurvival.wordpress.com/2008/04/04/more-on-why-to-use-qu...
for pictures of what happened when I turned on my TV one day.
Also, if you have a cheap cable, it may drop out packets along the way because of interference, a badly soldered cable connector, or other reason. I like knowing that if my cable suddenly fails, I have bought a quality cable from a premium reputable manufacturer like Monster.
When 1080p and HDMI CEC and other features came out, I spoke to the guys at HDMI Licensing and even they said that not all HDMI cables could pass the full signal.
As for USB cables, maybe they don't make your pictures look better, but think of USB 2.0 and even faster USB cables, and I don't want to sit around and get a cup of coffee while my 10 Megapixel pictures load or I'm doing a backup to an external drive.
Again, just my thought on this...

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