Adding Songs to SD card

[Scarecrow]

Do my need to take the sd card out of my unit to add songs

[electro_handyman]

No, you can transfer the music with the Zumo connected to your computer, but probably should not be running Express or Basecamp as they may put locks on access(though I don't know for certain).
You do need a folder named "mp3" in the root of the sd card, other than that it's just copy/paste from your computer to the mp3 folder.
You can have sub folders for sorting your music if you would like. I have mine sorted 1st by Genre, then by individual artist.
The XT will still see all the files and allow you to select how you want them played.

[HipGnosis]

Note: If you have any .mp3 files in the internal memory /mp3 folder, the Zumo won't show you the SD card as a source for playing music.