There are two broadcast standards, 720p and 1080i. There is a never ending debate on which one is "better". I think SONY has just released a 1080p display, Now, no one is broadcasting in that format yet, if ever, but it will upscale everything to that resolution.

If your looking at standard CRT (tube) displays I think right now 1080i is your only choice among consumer grade monitors.

So I guess I have no real answers for you! But I wouldn't worry about the difference between 720p and 1080i right now.