To rename a Solaris 10 server, simply change these three files and then reboot:
/etc/hostname.hme0 (change hme0 to whatever the network interface name is)
Another piece that makes sense to change, although not necessary is the dump space where you save crash dumps. To fix this is also easy:
mv oldname newname
dumpadm -s /var/crash/newname
To change the IP, all you need to do is change the IP address in /etc/hosts.
Note: /etc/inet/ipnodes may also need to be changed when using IPv6.