Upgrading software

I am in the midst of upgrading 3 servers , all in paralell, not an easy task, one is on the extranet, the other is the main server, and the 3rd is the index engine db. We have to be very careful with the ports, as the sofware has to have the same ports as the old installation. It should be ok now, with the plan in hand nothing can go wrong right? I'll review the plan again.

Leonardo.