Default values when adding new datarow

Hi.
I have wired up a dataGridView, a bindingSource and a bindingNavigator on a
WindowsForm. The DataSource for the bindingSource is a DataSet containing a
table, say Orders.
When the addNewItem button on the navigator is pushed, I want to provide
some default values for columns in the new row in the grid: e.g.
CustomerNumber and OrderNumber (incremented by one). What is the usual way
of doing this? A code sample would be appreciated.

Gudni