To get 1080 (anything), you MUST buy a 1080p TV.

It is really common sense—every TV that I have ever seen sold in the USA that was advertised as 1080i/720p only had a pixel resolution of 1366×768 (or something similar). That is to say that a 1080i signal will be down-converted by your TV to 720p. It is simply a matter of hardware limits in that, a 1080i TV does not have enough pixels to produce a 1080 lines of resolution. Irregardless of what any salesperson may say, if your TV could handle 1920×1080 resolution it would be sold as 1080p. 1080i is simply a marketing ploy—I am amazed that it has held up as long as it has. If your TV is 1080i, simply use 720p.