when converting to 16:9 (i just figured this out recently after 1.5 years) i use virtualdub, select the resize filter and with the filter loaded, select crop, and crop 60 from the top and 60 from the bottom. then configure the resize filter to the normal size of the video (for me it is 720x480). in the the box thats labeled filter mode you need to select either precise bicubic or Lanczos3 (this will prevent the interlacing artifacts you are seeing) these filters will help add lines to sharpen the enlarged video. what program are you using for editing?
when converting to 16:9 (i just figured this out recently after 1.5 years) i use virtualdub, select the resize filter and with the filter loaded, select crop, and crop 60 from the top and 60 from the bottom. then configure the resize filter to the normal size of the video (for me it is 720x480). in the the box thats labeled filter mode you need to select either precise bicubic or Lanczos3 (this will prevent the interlacing artifacts you are seeing) these filters will help add lines to sharpen the enlarged video. what program are you using for editing?