Your biggest bottleneck is going to be the Bryce render. Do you have a lot of disk space? If so I'd suggest you render AVI full frames uncompressed or bmp frames. I did a StarWars title scene for a cubscout awards night. The animation matched the StarWars Music which was 2min 31sec or something like that. The 640x480 30fps render was over 600meg! The point is the first render looked like crap because I chose too much compression. I had to wait 3 days to render again and it takes just as long because Bryce renders everything as bmp frames and strings it together at the last anyway. When I added sound in movie maker I tried several default mpg DivX and finally settled on a Quicktime format about 10mb. I chose this because the file was shown from a laptop and didn't have to download from the internet. If I was going to post I probably would use the mpg4 v2 that produced a 1.3mb file. If you use uncompressed you can always compress with whatever you are adding your sound with. If you use bmp frames you can even postwork effects onto the frames or layer titles.