Refresh rate and contrast ratio

I am looking at buying TVs and the two questions I have about the TV (LCD) specifics are:

is a 120 Hz refresh rate noticabe? I see TVs out there that have a 240 Hz rate. I know what this means but I am not sure if I would notice the difference when watching sports.

Also, the same question for the contrast ratio. At what point is the human eye unable to tell the difference? Is it 80,000 or 100,000? And what is a dynamic contrast ratio?

Thanks

I am looking at buying TVs and the two questions I have about the TV (LCD) specifics are:

is a 120 Hz refresh rate noticabe? I see TVs out there that have a 240 Hz rate. I know what this means but I am not sure if I would notice the difference when watching sports.

Also, the same question for the contrast ratio. At what point is the human eye unable to tell the difference? Is it 80,000 or 100,000? And what is a dynamic contrast ratio?

Thanks

I really can't speak if the 120 Hz is noticeable.

However I believe the dynamic contrast ratios are a moot point because all the different manufactures use a different scale...so Sony could say their dynamic contrast ratio is 100,000 and Panasonic could say it is 500,000...but they could actually be the same. This is the way I understand it. I could be wrong however.