I just need a way to have this server notify me of ip change so i can update my domain register info to point to new ip.
You want to update your domain register? How often is the IP changed. You might be doing this several times an hour. What about using DynDNS.org to register your domain dynamically for you? Or am I not understanding your post properly?
In any event, there is a fairly straightforward way using cron to see the IP on a scheduled basis. This is similar but different from what Arne is suggesting. I ran into the same problem a few years ago. We got sophisticated and wrote a script to check to see if the old external IP had changed and if so mail the new IP to us, but it got too fancy and I can't find it at the moment. A basic way to do this is in concept is:
1. Write a script that sends the ifconfig info to a temporary file eg /sbin/ifconfig > /tmp/temporaryfile
2. In that script, mail the info from the file to yourself. eg mail admin@yourdomain.com </tmp/temporaryfile
3. set this script up as a cron job using standard SME custom templates (or the crontab manager contrib). You decide how often you want the cron job invoked.
So you get regular, every second if you like, emails on what the IP is, determined by your crontab settings.
See the manual on custom templates and crontab for more information