So I get a call from my ISP telling me they need to change all my IP
addresses, they were leasing them and the leaser wants this IP range back
and they have given me a new set of addresses.

My question is, is there a way to change all of my configured public IP
address easily? I was hoping that I could just open the config files and do
a find and replace. Is that possible for most of my needs?

We currently run NAT, http proxy, and have about 5 public IP's going to
email servers and terminal servers.

Thanks for any suggestions.