If your iPod has music on it from actual CDs and you do not want to lose the songs you may need a program to transfer music from iPod to computer so that your music is not lost in the process. First, be very careful when you hook the iPod to the computer for the first time. If you accidently sync it with a computer and the music is not already in iTunes all of the items on the iPod will be lost.
There are a few third party programs that will enable a user to copy music from the iPod to the computer. The one which is recommended most frequently is Yamipod. It is a free program that will transfer the music from your iPod to the computer but it will not transfer other information such as playcounts or ratings.
There are several other free programs that will do the same thing. Pod Player, Floola, and Share Pod will all do the job satisfactorily. As will iDump and iPodrobot.
If you want to transfer videos too you can use CopyTrans. It will also preserve all the ratings and playcounts that have accrued. It will also transfer videos from the iPod to the computer. But this program is not a free one, it will have to be purchased.