OG, the aspect ratio of renders are (approximately) 1.78. I create dailies at 1024 x 575 and use 640 x 360 if I'm checking lights or what not. So to answer your original question, I'm not rendering at 1920 x 1080 yet but that is the goal. Since the aspect ratio never changes, then I know it will be right as you have mentioned. I imagine that your renders will not be letterboxed when displayed on a 16:9 screen. Like you, I am still finalizing post-production workflow. My Windows boxes run AE7. Since I've switched to Mac, I have no serious composting software but my Renderman-centric workflow will probably guide me towards Pixar's "it". Finally my DAW of choice is Cubase linked to MOTU 896 converter. Like you I plan to create videos but school has prevented the serious pursuit of that goal ATM.