Yahoo SBC DSL Express ip renumber challenge

When you buy Southwestern Bell's Yahoo DSL Express package, you are to be dynamically allocated your ip's. I hoped that if I didn't turn off my modem my ip wouldn't change. I have discovered that the ip changes DAILY is appears. This is a problem for me and I'm not willing to spend an additional $20 per month for a physical ip (they give you 5 which is stupid by the way, they should save ip's and only give 1 and then maybe a lower cost upgrade). You only need 1 ip really (if you enable ip forwarding on your firewall).

SO, DOES ANYONE HAVE A SOLUTION TO KEEP MY DSL MODEM FROM REBOOTING (OR REQUESTING A NEW IP)???

Does anyone have the Speedstream 5100 (I believe that is the modem model I have in my package) and know that modem well enough to TURN OFF this "feature"?

THANK YOU!

Walt Lane