Internet Sharing...HELP

Archived from groups: alt.comp.networking.connectivity (More info?)

I have got 2 computers at my place. One of them uses a client to
connect to the internet. The Client binds to the MAC address of NIC of
this computer. The Computer also acts as a web and ftp server on a
large network. The Computer has two IPs. One for Internet Connection
and other for the web and ftp servers. The IPs used are:

For Internet:
IP:- 10.12.63.123
Subnet Mask: 255.255.255.0
Default Gateway :- 10.12.63.1

As A FTP and WEB Server
IP:- 172.16.5.51
Subnet Mask:- 255.0.0.0
No Gateways.

Now I want my another computer to be connected to the nwtwork such that
the two computers can access the internet at the same time as well as
the other computer appears as a seperate computer on the LAN and is
able to provide and access services for the 172.x.x.x ip ranges as
well.

I managed to connect the two computers in an Ad-Hoc style. And then
tried using Microsoft Internet sharing and WinProxy but it doenst seem
to work worse the first computer is no more recognised on the network.

Please Help.