Grr - Connection Help (Smart People)

[Leighland]

Well, I have one of those DSL modems that changes the IP address every day. I want to add Server Online/Offline support to my forum but I can't figure out how to get it to work. If i use my Default Gateway it says offline, and If I use the Public IP address, it also says offline.

Any ideas? I'm not using a router or anything.