The following is for NTSC -- the US standard for television. 640 x 480 is square pixel standard. 720 x 480 is rectangualr consumer DV (Digital 8, Mini-DV) 720 x 486 (I think it's 486) is DV-CAM or the Professional DV. NTSC runs at 29.97 frames per second. If you're using Premiere, none of this is relavent. Render your file at 640 x 480 at 30fps and Premiere will auto stretch and convert the frame rate for you, no problem. Or, if you'd rather avoid the huge files of uncompressed animation (but sacrifice the uncompressed clarity if you're going to do composite work later), render at 720 x 480 and use your on-board DV compression; I use the Sony DV codec on my Sony VAIO. Carrara will automatically use the compression and will generate non-square pixels. So, if what I create in Carrara (or RDS) is going to be used AS IS in a premiere project, I just render it out for the DV codec. If I'm going to manipulate the image in After Effects or any other package, I render at 640 x 480 uncompressed. Hope that's helpful. - Dex