compressing highly detailed footage?

Hi,

I have a short video-art project where I'm using both original HD footage (16:9, 1080p) and footage from an old b&w film from 1940 in (4:3, 720*480). I decided to work with a 720p sequence in FCP 7. Obviously, the original footage looks better when I export the 720p sequence to a .mov file. Now, I need to send a screener of the project in 360p or 480p. When I use Compressor to compress the file and change the dimensions I get the B&W fragments very clear but the HD footage looks bad. Maybe it's because this footage is mostly long shots of landscape and parks, and therefore highly detailed. I also shot the footage with a hand-held camera, so there are small movements (which maybe make it difficult to compress)

I've tried to work with H264 in mov and H264 in mp4. The second option gave better results but still not good enough results. Any suggestions how to create a file where both the new and old footage look clear?

Thanks a lot!