What you need to do is go to the Palm developer site, and follow the download links as if you're going to download the Emulator (which of course, you already have). This will eventually take you to a page that offers a .zip file filled with skins.
This does not include the Handspring skins. I got these from Handspring when they were a separate company, but don't know where someone would get them today. -- For information on using the Palm Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/support/forums/
