1. You can file a separate return but it must be mailed and on the SSN of spouse write "Spouse nonresident alien."
2. You can also file a joint return. You will get standard deduction of $10,700 and exemptions for both of you.
You must both declare your worldwide income for 2007. If you have any foreign income, and on that income you paid taxes in the foreign country, then you can claim foreign tax credit. Read:
Your U.S. Tax Return: U.S. Citizen or Resident with Foreign Income
You will complete forms W7 (application for ITIN) for your spouse and attach with your tax return.