Go to Windows Explorer,
Go to the 'Tools' tab,
Select 'Folder Options',
Go to the 'View' tab,
Locate option(s) regarding 'Hidden Files and Folders'
Select 'Show hidden files and folders', then click Ok
Browse to your iPod under Windows Explorer
You will see a folder called 'IPOD_CONTROL'. Browse into this, and there'll be a folder called 'Music'.
Copy this folder to your hard disk
Right Click this folder once the transfer is complete, click properties, uncheck hidden, click Ok.
Go to iTunes, go to its 'Options' or 'Preferences' (I'm not too clear, it's called Preferences in OS X).
Select the 'Advance' tab, and ensure 'Copy files to iTunes music folder.....' is checked, then click Ok.
Then click, File, Add to Library, and select the 'Music' folder you copied over.
Whilst you wait, go back to 'Folder Options' and re-hide all your hidden files. Enjoy.