My 61" Samsung LED-DLP does 120hz processing. I am very happy with it.
I've never noticed any weirdness with movement. Not with movies, normal TV shows, or sporting events. It all looks great. We watch a lot of football, and the picture quality is darn near as good as actually being at the game. I've never noticed anything strange regarding quickly-moving objects. It just looks, well, real.
But of course, this is 120hz processing on an old-school LED/DLP set. Things are a little different with LCD & flat-panel TV's...
The best thing you can do in TV shopping is as others have said. Read up on the models and learn what the "optimal" settings are. Then go to stores, be a jerk, and start adjusting sets. While shopping for my TV, I think Best Buy got tired of me resetting half of the TV's every time I'd show up.
And yes, it takes about 15 minutes of AVS searching to know more than 90% of the big-box employees do about TV's.
