Check how much disk space you have left on the iPod. Do not believe you will always - if you have done so, get 5,000 songs on it. I have a 30gb iPod. I have only 1,150 songs on it and it is using 15gigs of space. At this rate I would only be able to get a little more than 2,000 songs on it.
Click the menu button and go to the settings screen then to the About.