India doesn't allow dual citizenship officially. They have already established the intelligence computer system at any Indian port. It is not advisable to use Indian passport after becoming a US citizen. When you take a US citizenship oath on 09/25/2009, your Indian passport will be invalid. However, Indian visa or OCI/PIO must be obtained in order to enter India. Of course, US passport is a must, too because your US green card will be taken away at the US oath ceremony and you won't be able to enter USA without US passport or US green card.
Originally Posted by RSMuser
N-400 mailing date: 12/15/2007
IL recd: 5/5/2008 or 5/6/2008
Interview scheduled: 06/12/2008 at 11:20 AM
Status: Case closed - Completed. Official US citizen.
Applied for US passport and US passport card: 06/13/2008
Received US passport: 06/21/2008
Received US passport card: 08/25/2008