In 2007 I was single and filed as such for tax return. But is 2008 I am filing as married. The exemptions with my employer is only me (my wife is not accounted for to adjust the withhold from my salary).
I am trying to prepare my taxes electronically through TurboTax. Is there a specific step that need be done to account for what should be more return (because more tax was taken than should be)?
Thanks

What you claimed on your W4 is not same as exemptions on your tax return.
You can file as married filing jointly (MFJ) or married filing separately. In most cases, it is better to file as MFJ. Read http://taxipay.blogspot.com/2008/02/filing-status-for-married.html