iTunes rentals pulled down to Mac OS X desktop vs Apple TV

[Kevin Callahan]

I started looking at the rentals and noted "This movie is available in  
HD on AppleTV"

I don't own an AppleTV for various reasons.  I downloaded a movie for  
rent (my first one) - and saw that the movie was only 1.6G

I suspect it's not HD given how small the file is.   Does anyone know  
if the movie rentals from the iTunes store to be played on your  
desktop or laptop are not HD ? if not, what's the resolution? and does  
it have something to do with DRM implementation on AppleTV ?

K