Hz doesn't have anything to do with the picture QUALITY, it has to do with refresh rate of the picture.
There's such a thing as "off brand" and then there's WAY off brand. I'd stay away from those tv's personally.. I deal with tv's on a daily basis and have seen the good, bad and ugly.
Stick with a name brand and you won't be taking it back every month or so because of defects. I personally like Sony, Samsung, Vizio (which is an off brand of samsung) .. Philip's which is a Magnavox, Pioneer or Panasonic's are good as well. Stay away from RCA, JVC, Daewoo, Polaroid... some of the other real cheap brands.
Personally speaking Vizio is a great television for the price and has amazing picture quality. If you have a local Costco or Sams Club purchase it from there, you can take it back for up to two years no questions asked and if they don't carry that specific television anymore they'll pay you out in cash to purchase another television.
Good luck, if you do decide to purchase the television anyways post up your results!
On a side note to THK as well, i'd steer clear from Plasma's. Yes they have high contrast and will give a very bright vivid picture but are extremely HOT and suck up lots of energy. Some (not all) are pretty heavy too! although they're thin they can still weigh in excess of 100lbs. Any new Plasma you purchase you typically don't have to worry too much about burn in on the screen because they have a setting in the menu that can clear most burn in, considering you havn't left it on a still picture for 24hrs+
Plasma is dying technology and LCD/LED is a much better alternative with more rewards to counter act the disadvantages.
