500K is probably too big. The best way to reduce the size of a file is to
eliminate or reduce the use of jpgs within it. Use vector shapes and a 500K
file quickly becomes a 50K file. Music is another place where you can build 
up
size. People will generate files at recording studio standards, and you real
ly
don't need that for the web. Use the lowest sampling and other settings as y
ou
can before it sounds bad.