Hi,
I am on F1-OPT status. I am married to a canadian national, who is resident alien in USA for tax purposes. I did not have any SSN and MEDICARE TAXES withheld from my paycheck as I am a non resident alien in USA.
While filing taxes for year 2007, as I was married on dec 31, 2007,Can I file my tax jointly with my husband as a resident alien.
Does it not conflict with my status as a NON RESIDENT ALIEN which I mentioned in the FORM W4?

Yes, you can file jointly with your spouse, as long as you sign and attach a statement to the return stating that you CHOOSE to be treated as a resident alien for all of 2007 and you declare ALL 2007 world-wide income on your tax return.