RE: What to look for when purchasing a Flat Screen TV?
If you're concerned about power usage (how I convinced my parents..) you can download a list of ALL the energy star TV's from the energy star website. I did that, deleted all the irrelevant specs and sorted it by size/power usage. We ended up getting an LG 42LV3500 42" LED LCD TV. We got it from Newegg for $600 with free shipping and along with a super cheap HDMI cable a few months ago. It looks great, the only thing is the speakers are pretty low quality, so you might want external speaker. One thing to watch out for about speakers is the audio output on the TV. Our's has L/R component, and 1 optical output, so if we want surround sound (and we do) we have to find something with a optical input. If you have a PS3 or HTPC, you really don't need any kind of smart TV. Ours can play MKV files straight off a hard drive via USB, which is all we need. Also, even though I can't compare it, ours is only 60hz, not 120hz or 240hz, but I really don't think it would make that much of a difference, and 60hz seems plenty fine, expecially seeing as most TV or games (PS3/XBOX) are around 30fps (I think).
And like Tjettzky said, stay away from weird name brands, like Best Buy exclusive or the really cheap ones. LG, Samsung, Sony, and I think Sharp are good. The biggest thing is probably picking the size you want, and reading reviews, from multiple websites.