Setting up Airtel Static IP

I have got a static Ip from Airtel. I need to know how to set it up. Below is the existing connection details.

We have 25 computers powered by Airtel.
From the broadband modem a switch/hub is connected.
From the switch/hub the client computers are connected.

Now we have got a static IP, i need it to be setup in my computer.

All the other computers will act as clients using dhcp.

The airtel guy who came to configure the static ip told abt NAT and Bridging. If this is the case, how should I configure Airtel bb for the static IP.

By configuring my computer with static IP, I should be able to access my computer from outside too.

Pls help me out.



Let me be more clear.
My company employees will most the time be in travel. They goto client places. If they need any data then they call us up and we send them thru emails. I want this to stop. What I am trying to attain is, when we get a static IP and configure it in our Server, they should access the server and get the data themselves rather than asking us.

Also we have another branch in Chennai. We are using a attendance software(Web based) which will be installed in the Server. They should access the software installed in the Server and login their attendance.

As you said, I will configure my 192.168.0.15 to my static IP 122.
If a person A in our client place puts the 192.168.0.15 IP and tries to access, normally many companies will be having dhcp enabled, it has the same series as we are using. Don't you think the 192 series the person A using is used in the client place?? then what happens?

For the above purpose only we even bought the Static IP.

How the above should be attained??