I think that's a little too much for a 450MHz. Pesonally, I would limit it to a Webserver, MySQL, FTP, SSH, SAMBA, and a mail server. Running X with it could be overkill, but if you aren't going to use these services much, no big deal. The main concern is the streaming media. The mp3 streaming is going to take a lot of CPU power. The webcam streaming could take a bit also. As for the distro, Debian would be a good idea IMO.
I would just suggest running the services I mentioned. and see if and where it bottlenecks. If it doesn't you might try the streaming cam, but I ahve to say the streaming mp3 really depends on how good of quality mp3s you want to stream. If you want something around 92kbps and higher, you would be pushing it with all the other services. You can try for sure, but I personally can't promise any good output.
Sorry, I don't have any real good links, but I do have a PET on the streaming media.