You’ll want good specs so you can actually enjoy your TV in the coming years as opposed to loathing it. Also, plan a few years down the road by knowing that technology does become obsolete. It’s wise to get good performance not just for entertainment pleasure but to keep your TV relevant down the road. This will help keep the resale value higher.
Make sure your TV is 1080p or 1080i compliant. This means a screen resolution of 1920x1080. It's the way to go moving forward with technology. Do not go with 720p. Anything lower than 1080p/i and with a different ratio (1920 : 1080 = 16 : 9) may provide lower, less enjoyable, quality when viewing your flat screen. Demand 1920x1080 and don’t settle for less. Watch out for pushy sales-people on 720p’s. It’s your money, therefore it’s your say. Having said this, know that standard DVD’s have a lower resolution than 1920x1080 and so playing them on a 1080p/i set will provide good quality, but not true, optimal, HD pictures. To truly take advantage of a 1080p/i TV, you’ll need to get a Blu Ray player.
Next, make sure you get a good contrast ratio. For Plasma’s the typical value is already very high at roughly 1-3 million : 1. This is where the better color vividness and distinction between dark colors comes from. For LCD’s, try to get 80,000 : 1 or better.
You’ll also want a good refresh-rate on your screen, say 120Hz, and a good response time… say 4-6 milliseconds (ms). These are factors in eliminating motion blur, which is more important on bigger screens. You don’t want to get motion sickness while watching action movies like Iron Man or every day sports.