First off I want to state that I have read prior posts on this similar subject but most are moving to another server or x32 to x64. I want to move to Zimbra 7 so I must first upgrade my OS, get server stable then move to Zimbra 7. So my inclination to upgrade the OS on my Zimbra server running Zimbra 6.05 currently on Ubuntu 6.06LTSx64 (AMD opteron) is the following:

1) Backup /opt/Zimbra (perhaps clone drive just-in-case)
2) update Ubuntu 6.06LTS till "up-to-date"
3) stop Zimbra and disable in init.d
4) upgrade Ubuntu via update-manager-core and do-release-upgrade to 8.04LTS
5) I believe this will require a reboot
6) Download and install Zimbra 6.05 for Ubuntu 8.04LTSx64 (AMD opteron)
7) Enable Zimbra in init.d and start Zimbra
8) Fingers crossed all will work properly?

From all the reading I have done this appears to be what needs to be done. Please tell me if I am wrong or right with these steps and if they have worked for you. Thank you.