Ubuntu 8.04.1 Server LTS

I am setting up a network of approx. 16 computers in a school lab. I am using Linux Ubuntu 8.04.1 Server edition and plan to use it as a DNS server for the labs computers. There is a modem with a Linksys WRT54 G router attached already, and I would like to use the Internet feed to service my lab. I have downloaded Bind9, Apache2, Open-ssh, and Putty. The lab machines are Dell PCs, running windows vista business edition.

My computer has two nics,
My question is how do i use this setup to serve the internet to the windows computers