Hello Sir,

Myself n my wife came together (L1 & L2 visa) to USA on December 2010. I filled my Tax as Single. But I need to amend it (want to file tax jointly). My wife doesn't have a iTIN. Do I need to fill W7, 1040NR and 1040X form? Please suggest the process.

Regards
Sudip

If you came in December 2010, you are a non-resident alien and would need to file a 1040NR or 1040NR-EZ. Your only filing status would be married filing separately.
You would need to amend your return to that.
http://www.irs.gov/businesses/small/international/article/0, id=96477,00.html