With analog (D-sub) connection between our WinXP PC (Nvidia FX5900XT)
and LCD TV (Hitachi 28LD5000TA) we are able to display a 1280x768
(15:9) aspect desktop. But if we use the digital (DVI-PC) connection
the maximum resolution we can display is only 1024x768 (4:3). Why
might this be? What might be required to enable a 1280x768 digital
signal to be output from our PC and or to be displayed on our
monitor/tv? The tv is PnP (no drivers req'd or available). The TV
owners manual does not list any DVI-PC resolutions higher than
1024x768.

check your refresh rates. My nvidia at 75hz will do 1280x960 but at
85hz I only get 1024x768. Also there is a program zip called
"coolbits3d" for nvidia cards that will unlock more advanced settings
for the card. I believe you can get it from download.com it is free.
if not, email me from the link on my site
http://www.empirevisions.com
and I will get a copy of it to you.
Eric