This video shows you a straightforward way for Windows users to transfer music from an iPod to your hard drive, without extra software:
1.Connect the iPod to your PC. If iTunes starts syncing (i.e., erasing) your music automatically, hit the X in the upper right hand corner of iTunes display, to the left of the search box, to stop it.
2.In Control Panel, Portable Media Devices, double-click your iPod.
3.In the Tools menu -> Options, in the View Tab, check "Show hidden files and folders."
4.Navigate to the Music folder. On my 2nd gen 'pod, the full path is
Portable Media Devices\GINA'S IPOD (F:)\iPod_Control\Music
5.Select all the music folders, and drag and drop them into a folder on your
hard drive, or directly into iTunes.
And you're done! The iPod music folder structure is strange and inexplicable, but once you move your files into iTunes you can set it to automatically organize your folder by artist and album to clean that up. (To do this, in iTunes Edit menu, choose Preferences and in the Advanced tab, check "Keep iTunes Music Folder organized.")