I married in November 2007. My wife came to usa in jan 2008. I was on OPT till sep 2007 and then after on H1B visa. I also want to claim my GC holder parents. How should I file my tax to get maxium return. I am an indian citizen.

You cannot file as single. You must file as married filing jointly or as married filing separately. It is likely that filing jointly will be best for you. You will need to fill out W-7 to get an ITIN for your wife and file at the special location indicated in the instructions to W-7.