We are getting ready for a major migration and are looking for some feedback on the macro steps we will be taking:

Current
- 32 bit
- Ubuntu 6.x (LTS)
- Zimbra 6.0 (FOSS)

Final
- 64 bit
- Ubuntu 10.x (LTS)
- Zimbra 7.0 (FOSS)

Step 1 - migration to new 32 bit box
- 32 bit
- Ubuntu 8.x (LTS)
- Zimbra 6.0 (FOSS)

Step 2 - upgrade Zimbra
- 32 bit
- Ubuntu 8.x (LTS)
- Zimbra 7.0 (FOSS)

Step 3 - migration to new 64 bit box
- 64 bit
- Ubuntu 10.x (LTS)
- Zimbra 7.0 (FOSS)