Prasad, the default state is hard coded in store core code in file checkout.ascx.cs at line 713. In this file at line 713 you will find following code snippet:

orderController.UpdateOrder(_orderInfo.OrderID, System.DateTime.Now,
"",
m_ShippingAddressID,
m_BillingAddressID,
_orderInfo.Tax,
_orderInfo.ShippingCost,
true,
1,
UserId);

In above code snippet the number "1" is nothing but the "Order Status" parameter. It is here where the default order status is set. If you change this "1" to "2", it will change the default "Order Status" to "Awaiting Payment" whenever a new order is created. The updated code should be as follows:

orderController.UpdateOrder(_orderInfo.OrderID, System.DateTime.Now,
"",
m_ShippingAddressID,
m_BillingAddressID,
_orderInfo.Tax,
_orderInfo.ShippingCost,
true,
2,
UserId);

However, you have to understand what risk this change brings to you. Consider a scenario where your visitor makes a purchase and goes to paypal and executes the payment and DOES NOT OPT TO COME BACK TO YOUR WEBSITE. In this case the order status will not be updated to "Paid" it will still be "Awaiting Payment"; this is so because the store updates the order status to Paid when the visitor comes back from Paypal back to store website. If the visitor does not return to your website from paypal then the order default status prevalis.

Ofcourse, not to mention once you make above code change you will have to compile the store project and create the new dll.

Hope above helps,

Sincerely,