I was on OPT from August 2007 to August 2008.

From October 2007 onwards I am on H1b visa.

Which tax return should I file this year? 1040 or 1040 NR?

Thanks

Is this October 2007 or 2008?
When did you enter the U.S. on F1? Are you married?

Sorry it was a typo - October 2008

- single

- entered in US on f1 for the first time in August 2005.

You need to file Form 1040NR-EZ and Form 8843 one last time for 2008, as you have not yet met the Substantial Presence Test.

For 2009, you will file as a resident alien.