Need to send Reminder emails.what is the best approach?

Question

Hi ,

    We need to send some Reminder emails to the employees using (registered) our web site application.we have to check the Date column in the database table and send emails to them who are very near to response due date Automatically.  What would be the best approach to acheive this with out affecting the web site performance. Either running Scheduled jobs daily or use a windows or web service.