The IRS will take a 25% withholdings from the winnings. However, the total tax bill will be 36% on the federal level. If you are using the IRS Publication 17 tables, it will give you a quick and dirty estimate. I am giving this number based on the prize amount without adjusted gross income, deductions and exemptions.
Also, you need to check the state local income tax rates too.
Amended You also need to check the NYS tax rates.