A few things I have learnt from having 3 iPods (a Touch and a Classic belonging to grandchildren, and a Classic belonging to my wife.
1. Have a back up - ideally on a second, maybe external HD of the iTunes folder including the music folder.
2. Set i Tunes to manually synch. That way each i Pod can synch what it wants and you wont synch a blank folder and lose stuff. To do this click on Edit, Preferences,Devices. then check the box "do not auto synch.."
3.In i Lounge( a good forum)you will see how to get i tunes off an iPOd, but if you set it as above, then in Start, Control Canel you i Pod should show as a drive and if you explor it you should find the music folder and you can copy and paste it to wher you want.
4. I have two libraries for the above reasons.Post back for further info from a rather shaky end user!!