That sounds about right more or less (depend on length of MP3). For the ipods, 30GB can store approx. 7,500 songs and the 60GB holds 15,000 songs.
The cheaper iPod nano are as follows:
1GB (240 songs), 2GB (500 songs) or 4GB (1,000 songs)
If your PC uses a 160GB hard drive, your 30GB iPod is like nothing. That's a lot of songs. You can have 5 of that 30GB iPod's and you still won't fill up that 160GB hard drive.