The VOOM channels are in 1280x1080i, i.e. HD-lite. This is all VOOM channels. At this format, the image has only 2/3rds of the original digital information. HOWEVER ... as many HD programs have been recorded using cameras having maximum resolutions of 1440x1080 or even 1280x960 (or lower), it is possible that a very good conversion to 1280x1080i could capture most of the original information.
All channels being broadcast in MPEG4 have been reported as being in 1440x1080i.
HBO and Showtime are being broadcast in 1920x1080i, but frequently at low bitrates, which causes some compression artifacts.
HDNET and HDNMV are in 1920x1080i and usually with good bitrates.
ESPN and ESPN2 are 1280x720p and usually with good bitrates. (Note: 1280x720p contains more image information than 1280x1080i.)
So I would recommend HDNET, HDNMV and ESPN as good examples of HD.
Many people will not notice a difference between a VOOM channel vs HDNET. Heck, many people don't notice much of a difference between upconverted DVD vs true HD. If you have a good HDTV set and you are a critical viewer, who knows what HD can look like, then the differences between VOOM and HDNET jump off the screen at you.
I have portions of the great HD demo program "Winged Migration" recorded from VOOM Equator HD back in November when it was 1920x1080i, again from Equator HD after it was down-rezzed to 1280x1080i, and from HDNET.
The HDNET version is best, with the November Equator HD very close, but the HD-lite Equator version has softer lines and lacks the jaw-dropping realism that HD can provide.
HD-lite does produce a pretty good picture, it just isn't a match for true HD.