windows 2003 small business server R2 <server based firewall configuration>

i need help, badly, with this set up
–> http://h1.ripway.com/kian/draft.jpg

coz when the firewall is enable all the machine that connected to the server cannot access to the internet so i need to configure the firewall when it is enable all machine can access to the internet. plus the firewall on the router

thanks ^_^