Well satyamy, you'll have to get Mobile Office activated from Airtel which costs Rs.500 per month. It will give you EDGE speed which is 236kbps and it will be unlimited. [Though you'll only get around 180kbps which is 22.5 KB/s]
You can use your Airtel mobile on the PC, only when you get Mobile Office activated.
If you try to connect from GPRS on your computer, your computer will show connected, but there will be no data transfer.
Earlier there were many tricks to use GPRS on PC, but they don't work now as Airtel have taken the required security measures.