First, there are regulations regarding whether you can treat someone as a salaried employee. A salaried employee is not eligible for overtime because they are considered exempt from the Fair Labor Standards Act, (FLSA), which, among other things, requires employees to receive overtime.
For example, simply calling someone a "Manager" does not mean they are Exempt from the FLSA. Incorrectly classifying an Exempt employee will result in paying the OT plus penalties.
Do not make this decision lightly. Check with your state's labor regulations and know what the Federal Requirements are for classification. You will need to consider how much you are paying and what the actual responsibilities of the salaried individual will be.
Here is a great primer from the Houston Chronicle's Small Business Initiative