Sharing the internet connection without using any kind of proxy software on BSNL Broadband


I have a BSNL Home 750 Unlimited plan at my school lab. There are 11 computers in my school lab, all are connected via switch using wired network. One computer is server and remaining 10 are clients having windows Xp on all machines. There are two Ethernet adapters on server PC. one is used for ADSL modem and other for connecting to the school LAN.I want to share the internet connection to all the PCs without using any kind of proxy software. I heard that it can be done by using port forwarding and virtual server configuration on the ADSL modem. I dont know how to configure these settings. If any one has done this kind of stuff then Kindly help me.:thumb: