You can transfer ringtones and music from another BlackBerry to another fairly easy. You have a few options. You can use the MicroSD card you used for your provious BlackBerry to your new one, and all your custom ringtones should be there. Another way is connecting your BlackBerry to your computer and use your computer to transfer the files from your old BlackBerry to your new one. You can also transfer data from BlackBerry to another using the Desktop Manager.
Your custom ringtones should be under X:/BlackBerry/ringtones
Also, some of the alerts from OS 5 is not on OS 7 anymore, but you can download them for free. Click here for more details about that.
EDIT:
For the music, there should be another folder under BlackBerry that's called music. That's where you would put all your mp3s.