You only need 1080i/p if you have a very large TV (because the pixels will be spread out more), and I mean like 50"+. For a 37" 720p is fine. Also HDMI 1.3 is all about the hardware, you won't be seeing hardware that will be utilizing 1.3 in a while, and even then it will be very expensive. The only highlight you have to worry about of 1.3 is that it can deal with higher resolutions (over 1080, and like I said, there aren't many consumer grade TVs that would carry that) and that it can support up to 90Hz refresh rate (once again, there aren't many TVs that can do that).
The other part, the one that is supposed to be a big deal is better color, it goes like this:
24-bit (normal color depth) = 16.7 million colors
30-bit (HDMI 1.3 only) = 1 billion colors
36-bit (HDMI 1.3 only) = 69 billion colors
48-bit (HDMI 1.3 only) = 2,800 Trillion colors
Now this is where it gets stupid. Why in the **** would you need 1 billion colors? Or even 2,800 trillion colors? There would be so many different shades of yellow that 50 billion of them would almost be identical. Understand?
One last part, is audio formats, specifically the lossless compressed digital audio formats. Now unless you have super-human hearing, or just an audiophile, this is utterly useless. I have a crappy surround speakers and they are perfect for me. I don't need to hear the camera man's breathing FFS. HDMI 1.3 is based for technology years from now. It is a complete waste at the moment.