xp as a gateway

How can I Configure a Windows XP system as a Internet Gateway with out Installing any Proxy.

You can set up a second network card and use Internet Connection Sharing. Have a look at these:
support.microsoft.com/kb/310563
support.microsoft.com/kb/306126

thanx for reply. if we do like this the ip address will automatically set to 192.168.0.1. I need a setup like if we give a gateway ip in the client it shuld coonet to the internet through the system which we have configured as gateway.

Your second card would set to 192.168.0.1, and that would be the gateway address for the PC(s) connected to that second card to access the internet. The first card on the gateway PC would connect to the internet directly via wahtever means you use to access it now