MPEG-2 to AVC conversion is useful only to get the same image quality with lower bitrate, hence smaller file size - yet, some quality will be lost, even if not that much. At that point, an alternative could be to do a nice upscale (that should be better than the average HDTV real time upscale), apply a slight deblock (useful for MPEG-2 encoded video) and possibly a light noise reduction, and have the NTSC 480p 29.97fps as 1280x720 59.94p or 1440x1080 59.94i, and PAL 576p 25fps as 1280x720 50p or 1440x1080 50i - I’d go with 1440 horizontal lines if the DVD material is anamorphic, as 1440=720x2, hence better upscale. So, any PAL and NTSC material, when upscaled, could be burned on a BD-R and be read by any BD player, from US or any other part of the world, without eventual compatibility problems.