It's also, I think, important to note that that the resolultion of 1080i HDTV is 1080x1440, which means that it's the same resolution as the digital projector, except not as (potentially) wide.

Minor technical correction. HDTV is 1920 pixels wide, by 1080 interlaced lines high. The digital theater projectors are a lower resolution than that.

In fact, many home HDTV systems which use LCD or DLP technology are lower resolution than that because I don't think anyone's made a cheap 1920x1080 LCD or DLP panel yet. The only systems that actually use the full rez of HDTV are CRT-based systems.