With WMV 9 they have been jamming 45 minutes and up to 2 hours of 720p or 1080p content on a single regular DVD and the quality is pretty impressive. The extra space and the advancement of the codec in HD-DVD is going to be even better.
That said, I want to see a 1080 show on Blu Ray disk go head to head with the same show on HD-DVD on a native 1920x1080 projector or other display type. Then I'll make a decision.
with an outside possibility of pushing it to 8 layers and 200GB. Both the 4 layer and 8 layer solution are still only in development and under consideration right now though.
Blu-Ray has more space though, I don't see why you would want HD-DVD instead.
It'd be like in 1997 if some companies banded together to make a "Super CD" format to rival DVD, with a lower storage ratio. Sure it might be cheaper at the time, but by 2005 (today), such a format would be painfully maxed out.
Blu-Ray should definitely get the nod over HD-DVD, in the long term its the better potential format.