The best thing you can do to improve the sound of portable digital is to go to either a lossless, or uncompressed file. Unfortunately that means your songs will take up a whole lot more space. Try this with one of your favorite selections; rip it from the original CD as an mp3 (probably the default on your current Palm), and then try ripping the same song in a lossless format (Apple Lossless or WAV or whatever the lossless version PC users have). Listen to each, one after the other, and see if that makes a difference for you. If it doesn't then go with a Nano or other smaller iPod. If it does, you may want to rethink your selection to something with greater storage capacity. I use a 60gb iPod Photo (now iPod Video) and have all my music in either lossless or WAV. I'm sure the earbuds you have are up to the task.
Marco
Marco