Hello,

I am on F1 visa since Jan 2004. What form do I need to fill, will it be 1040 or 1040NR.
In past I have been filling 1040NR, when does I need to start using form 1040.

Please advise.

In 2008, you are still non-resident.
You can file your 2009 tax return as resident.
Read about F1 tax filing: Your U.S. Tax Return: The U.S. Visas