the term HD applies mostly to television sets, which just recently have started moving towards greater resolutions... also when it's about TV resolutions, it's only the vertical pixel count that matters (if it says 720, it means you get 720 lines of pixels across the hieght of the screen)
and given the fact that an old CRT telly is 480 pixels tall :o... anything above 720 is considered hi-res... what's really amazing to me is how on earth did they manage to interpolate such crummy resolutions over a 40+inch screen?
anyway, this just goes to show yet again the superiority of our PC gaming rigs over consoles!!

try running a PS3 at 1600x1200... ;)
Cheers
HarvesteR