I am a bit confused whether I should fill 1040 "OR" 1040NR for to file my tax returns.

Details about me:
I am on F1 Visa status finished my Masters degree requirements from Dec 2003 - Dec 2005, during this period I interned with a company.
Currently I am on OPT.

Appreciate you help.

- Siddhartha

Sorry for following up on my email :).
I have one more question. 1040 has some extra benefits over 1040NR like "educational credits", "credit for elderly and disabled". So I am wondering if I fall into 1040 category.

Thanks,
Siddhartha

You must file Form 1040NR for 2005.

In 2006, you can file as a resident alien (filing Form 1040).

I went through the instructions in details, at:
http://www.irs.gov/pub/irs-pdf/i1040nr.pdf

On page 2 of 45, I pass the substantial presence test which is also called
The green card test. Does that mean this makes me "resident alien for
tax puproses" and I can fill 1040.

Any help redgarding this will be highly appreciated.

- Siddhartha