I have to format the harddrive and start from scratch. How can I backup/save itunes? last time I lost all

I have a 40gb external hard drive and that's where I keep all my music and pictures. When I've had to start from scratch at least the only thing I lose are my playlists in itunes.

I do the same but also burn a dvd with all my music on it. This way I always have a hard copy of it too.

Windows or Mac?

Copy the information to another drive or burn to cd/dvd. I've done it many times. The only thing to be concerned about is DRM. When you transfer the somgs back onto the PC you may be asked for the username & password used to purchase the songs before you can play them. I believe the songs purchased from itunes gives you 5 times the songs can be transferred.....and this is the main reason I will not purchase music with DRM. I can wipe my drive and reinstall everything at least twice a year.

Be sure to back up everything in: %homepath%\My Documents\My Music\iTunes

The "iTunes Library.itl" and "iTunes Music Library.xml" are really the most important file in there that links iTunes to your music.