720p is classed as a native resolution for most games, i.e. this is the maximum and optimal setting they are designed to run in, so you are seeing the game as intended.
If you switch to 1080i, your are "forcing" the 360 (or TV) to upscale the image to a higher resolution. The difference is in the "i" - the image signal is interlaced - this means that first, the screen displays half the lines of the image (e.g. line one, line 3, line 5), then it goes back and displays all the lines inbetween these that it missed on the first, but so fast that hopefully you shouldn't notice it. However, this can produce noticeable artefacts on the screen - it can lead to a very slight loss in quality, and in some cases (dependent how fast the TV refreshes the screen and the framerate, and also how cheap a TV it is) fast on-screen movement can produce visible "tearing" or smearing. Now, most folks might not even notice it, but like I said, it depends on the quality of the screen. It's not too different (although not quite as drastic) from watching a normal TV signal on a big LCD screen - it looks pretty crappy because the stanrd 480p signal is being upscaled to match your hi-def ready TV
Now, 1080p, on the other hand, does not interlace, and should be a simple upscaled verson of 720p so should maintain a decent picture. If you TV supports 1080p, then it may be worth trying that for fun and ignoring 1080i altogether.
At the moment, I think only one game (Virtua Tennis? I'm mot sure) is the only one designed to run in 1080p, so you will be best with 720p. Eventually, as more TV's come with native 1080p built in, we might see more game developers building that into their games, That will look awesome!
Log in to comment