We've got a current network edition deployment running on Ubuntu 6.06 32bit, and we'd like to get it up to Ubuntu 8.04 64bit. What's the recommended path for this? Is it possible to just follow the 32 to 64 bit instructions on the wiki, or do I need to do it in a two-step process? If so, what's the process for performing a dist-upgrade of Zimbra and the OS?