Connect the Ipod, if its in Disc mode, it'll appear in Explorer as a removable disk.

To set disk mode http://docs.info.apple.com/article.html?artnum=93651

Turn on the ability to view hidden folders and you'll see a Music folder. In here are a load of sub folders which contain all your music currently on the Ipod.

Copy this off to another location on your PC (music library folder etc) then you can connect the Ipod and not be too worried if it wipes it.