[c-nsp] [cisco-nsp] migration plan

[shadow floating]

Hi guys,
I'm delegated the responsiblity of migration of our existing network
infrastructure to a new design with new network devices and i should
minimize the down time to least possible time
we are migrating from a router connected to a software firewall and
just 5 access switches and 1 distribution switch to real network
infrastructe with 2 internet connections and 2 routers hotstandby
connected to 2 hardware firewalls and new vlans design...any adivce or
comments or something i should take care of that people always forget
about?
any advice will help

thanks alot