Help me save my Unix box. I've had this Unix box (Enterprise 450) for about 7 years now. It was being used as a file server for a Macintosh Prepress department. All of our networking was done through Helios Etharshare. I am still currently up and online (however the location has changed). Our ip configuration (company wide) originated way back before internet was really anything global. Anyway, Kodak set up a system for us back in the mid 80's and assigned the equipment a 129.# ip address. Since then every piece of equipment we added (yes bunches) all were given addresses in this old netmask range. Now that we have relocated, we are changing all of our address to fall inside a 172 range. How can I change the ip of the sun box without losing connection to the other network (available still through a T1 connection and pc router)? 
PS I'm only dangerous with Unix. and the OS hasn't been upgraded in maybe 5 years or so. I think I'm running Solaris 2.4.
First, are you adding the 172 address as the only address (getting rid of the 129)?
Second - run uname -a - it should tell you what version of Solaris you are running.
Third - look to see if you have an /etc/hostname.* file - see if the * portion is an interface.
Post the info you gather back here. Also take a look at Configuring TCP/IP on the Network (for Solaris 2.4)