Try this:

strUpdateCommand = "UPDATE Order SET " & _
"Shipped = 1, DateShipped = '" & now & "' " & _
"WHERE ..."

Open Connection

Dim myDataRow As DataRow
For Each myDataRow In OrdersToBeProcessedDataset.Tables("Orders").Rows
' initialize fields with values
myDataRow("Processed") = 1
myDataRow("DateProcessed") = NOW
UpdateCMD.ExecuteNonQuery()
next

Close Connection