If it's any help the Avid Media Composer (1000, 9000, symphony) all want 720x486. What you will want to do is find out the correct Codec for what you want to sell. Every edit system has a different standard. Notice that AzChip and I both work @ different places and we both have different standards...you will find the same anywhere...even each TV station in your town has different standards. If you can render with the correct codec in the correct format (avi,quicktime) you can save your client hours in importing....a 720x540 .psd seq thats 30sec takes 45min for my avid to import...where as the same sequence with the avid codec only takes 45sec to import. For instance if we wanted an animation for you for our Sonic DVD authoring station it would have to be 720x480...I have no ideal why even a piece of video can't be standardized :) Long and Short: Every place is different and will have alternatives for you...