My condition is below:
1. I got hi-b visa at October 15,2005.
2. I arrived and worked in New York at October 30,2005.
3. I got my social security card.
4. I got salary for two months.
Now, I am filing the income tax return.
I do not know if I am American resident or not.
I do not know what kind of form should I use to file my imcome tax return, form 1040 or form 1040nr.

You are not yet a resident alien, as you have not qualified for the Substantial Presence Test.

Right now you are a dual-status alien, which means that, if you file immediately, you should file Form 1040NR AND Form 1040. This is a complicated return and you should get professional tax help to file it. You will not be able to claim the $5,000 standard deduction if you file dual-status.

If you want to wait, you can file in mid-June 2006 and file as a resident alien, filing Form 1040, under the First Year Choice. This will allow you to claim the $5,000 standard deduction if you wait. For this reason, I recommend waiting.

File Form 4868 to get an extension by 17 April 2006.