How can I calculate what the difference in taxes would be to work in Bucks County, PA as opposed to working in New York City? I live in Bucks County, PA.

Here's a site that gives some comparisons between state tax rates. It seems that in PA you have a flat 3.07% with no exemptions, whereas in NY it's a progressive tax that hits 6.85% for income > $20,000, but with $15K deduction for married filing jointly. I think it's safe to say that for most cases the taxes in PA would be significantly lower than in NY.

The Tax Foundation - State Individual Income Tax Rates, 2006

If you want to dig further, do some Google searches and you can get the actual income tax forms and instructions for both PA and NY.

Ebaines had hit it on the nose; I have nothing to add.