A common misconception, but you do NOT need 6 months to be able to visit the USA under the visa waiver scheme. If it is not valid for 90 days when you arrive, you will be admitted intil it expires.
If you think I'm making that up it's here on the US London Embassy website :
http://www.usembassy.org.uk/cons_new/visa/niv/ passport_validity.html
However India does require 6 months validity AND a visa, obtained in advance, so you will have to renew anyway. You'll get the unexpired validity tacked on to your new passport so you won't lose out.