Heres some things to keep in mind, I recently bought me a flat panel tv..
1080p and 1080i are DIFFERENT.... 1080p is the superior of the two, however any tv less than 50-some inches isn't going to give you the full 1080p experience.
Another thing to consider is the Contrast Ratio. The greater the ratio, the better picture quality you will have. My tv is 42' with a 10,000:1 contrast ratio. Some TVs even the larger ones are only like 700:1, so be careful... if the ratio isn't printed on the information card be sure to ask.
Make sure your tv has a BUILT IN digital converter box thingie, otherwise your nice, wonderful HDTV can't display the HD without an external box.... fun fun fun, so make sure you have a tv that has one built in..... most do now-a-days I think, but still best to make sure.