Just tried the cineform 15day trial & I see it make a nice copy of the original (about 30% bigger on my test clip) I can open it & scrub about in it in Virtual dub in real time but it just hangs the preview screen in Vegas 5 if I select 720 60p? Now If I select any other resolution for the project its runs great? Anyone have any ideas why 720p is not working?

I think the HDV enhancements that occurred between Vegas version 6 and 7 make all the difference in the world.

Its just really strange that a 720x60p Cineform codec avi plays realtime in Vegas 5 if you put the settings to 1080p?

Probably due to some processing priorities embedded in the software.
Only Sony Media knows for sure.