Is there a way to un-sync my iPod from one computer and then sync it to another computer with iTunes without losing all my data or downloading software?

Hi, I'm selling my current computer that my iPod is synced to and want to un-sync (I think the correct term of phase is) my iPod from my current computer, so i can then sync it to my new computer without downloading any software or deleting all my data. Is this possible? If so, please tell me how. As usual, any help would be helpful. 🙂