Great howto

I'm almost there but I can't seem to access the internet from my lan. All my pc's get an ip and can talk to each other as well as the server/router. The server has internet access but for some reason I can't get it to forward internet traffic from my lan I've tried dns and ip's nothing gets out. By the way most of my lan consists of windows pc's if that makes a difference. Any help or ideas will be greatly appreciated.

Thx Preston