iTunes Library Question

I friend of mine has a huge iTunes library with a gazillion playlists.
All his music however is stored on an external hard drive.
I am planning to wipe his drive and do a clean install.
Anyone now whats the best way to approach this?
To restore it?
Or if anyone can point me to a hyperlink with the appropriate info, I would really appreciate it

I know you have to save the iTunes folder on the main OSX drive as it points to the external drive. I think once you install SL you can copy the iTunes folder back onto the main drive and all should be well. Try the support pages on the Apple site. If I get a chance I will try to find the link for you.

If the entire library is on the external then when you've done the clean install simply open iTunes, and point it at the library on the external drive by going to preferences and changing the position of the library.
Then import the songs.

Thanks,however......

My big concern is his massive playlist.
How do I back up this?
Is it just the xml file?

Yes, open it and check the data.

Huh?

Check the data?
When I reinstall his OS, and iTunes is this file what I use to restore his playlists?

Yes it should hold all the relevant info.

Here's a link to Apple's explanation of xml files in iTunes.

What are the iTunes library files?