Well, you either need to reboot so the files will be read again, or use the source command:
which will reread the files...
You need to change two files (not sure if it's neccesary to change the second, but it works for me). The first file is /etc/hosts ie:
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain computername
The second file is /etc/sysconfig/network ie:
That should do it....