I am married and living in Los Angeles(CA) from August 2010 (less than 183 days in California)on L1 Visa. I have dependants to claim(my non working wife and son). Suggest me whether I should file as a resident or non resident.Some agents are saying we can file as a resident and some of them are saying we should use 1040NR EZ(Non resident). Please confirm

You have two choices.
Choice 1: You did not complete SPT in 2010, you can file non-resident tax return. You can also deduct moving expenses for the family. Use Form 3903.
Choice 2: You can file resident tax return as Married Filing Jointly and claim your son as dependent. You must wait to file your tax return till you meet the Substantial Presence Test in 2011. Your U.S. Tax Return: Substantial Presence Test (http://taxipay.blogspot.com/2008/04/substantial-presence-test.html)
You must both declare your worldwide income for 2010. If you have any foreign income, and on that income you paid taxes in the foreign country, then you can claim foreign tax credit (Form 1116) or you can use Foreign Earned Income Exclusion (Form 2555). Read: Your U.S. Tax Return: U.S. Citizen or Resident with Foreign Income (http://taxipay.blogspot.com/2008/03/us-citizen-or-resident-with-foreign.html)
You will complete forms W7 (application for ITIN) for your spouse and son and attach with your tax return. You can also deduct moving expenses. Use form 3903.
If you decide to file as Married Filing Jointly as First Year Choice, you must attach a statement signed by both of you to your return stating that you qualify to file as residents as First Year Choice and that you CHOOSE to file this way.