If you have a router and modem its usually easiest to set the modem up as a bridge and let the router's internet port get the public IP address. Do note though that some types of DSL implimentation may not work with this (as you may have found out).
In that case set the modem internal (LAN) IP to 192.168.0.1, the router's internet IP to 192.168.0.2 and the router's LAN IP to 192.168.1.1. You may also need to set the internet gateway setting on the router to 192.168.0.1 so it knows to use the modem in order to reach the internet.
If you use the same IP range on both sides of a router it cannot perform its duties as a router and will not work, which I believe is what has happened as most SOHO devices seem to ship with similar factory confiugrations. Hope this helps!