Anu, here's a search for curry leaf on the Asian Vegetables forum. Some of these threads discuss where to obtain plants or seeds:
http://search.gardenweb.com/search/nph-ind.cgi?term=curry+leaf&forum=asianveg&forum_name=Asian+Vegetables

Here's a site where you can learn your zone. Enter your zip code at the upper left:
http://planthardiness.ars.usda.gov/PHZMWeb/

You can type your zone/location info in the Zone box when you post, but if you want it there permanently you'll have to enter it on your Preferences page (which you can access from the link just above the "Preview Message" button after the last post on this thread).