I have just recieved my new ATV from the States and connected it to my Beovision 6 as follows:
HDMI to DVI connector with a HDMI to DVI cable
Analog sound connector to PC sound in (AV3)
This works like a charm. Initially the resultion was set to 480 but when I played around with higher resolutions I was suprised to see that 720p also worked. I do not yet have my recently aquired BV6 HD upgrade kit installed yet.
I played some HD content from the movie trailers section and podcast and I can see a major quality improvement.
I am still wondering why the 720p works. Tonight I will install Boxee and XMBC and see how that works.