Upgrading to Leopard - backup needed?

Hello,

I'm not the greatest computer/mac expert out there and would really appreciate some advice :)

I'm about to upgrade my MacBook running on Tiger 10.4 to Snow Leopard.
I've seen how to clone a drive with all apps and preferences and so on, but what I'm wondering is if I can store all my music on an external harddrive, put in the installation dvd, format my harddrive and then install leopard?

Assuming all I want to keep is my music? Or is there incentive to take backup of something else, something important I might have missed?

Thanks in advance :)