Help configuring a shared DSL connection.

I am decided to use Linux or Windows 2003 server in the pc i have with the DSL connection, it has 2 network cards, one receives the DSL connection and the other one sheres it to the LAN.

Actually, i hava a pc with WinXP as the "server" sharing the connection, previouly, i was using the ICS of XP, but he broadband was not the real, so then i moved to use WinProxy, the broadband problem was solved, but with both (ICS, WinProxy) i have some limitations, the ports are configured in Winproxy, but the clients cant access the chats or play online, and other restriction im forgetting. According to my ISP, i have complete access, so it is configuration problem.

So, im planning to move this "server" machine into a real server, usign Linux or Windows 2000 or 2003. I want to prove both to see how they work.

Can you help to solve this problem. i have this data:
Pc with DSL connection: 1st net card (it receives the DSL):

ip 200.95.104.50
subnet 255.255.255.255
gateway 200.95.104.50
dns 200.23.242.202

The 2nd net cart:
ip 169.254.132.103

well, this last one is the card that is sharing the conection to the LAN, the clients have ip in the range of 169.254...

Any help is apreciated.