from my past post, pls note that i mentioned developing a sepearte application [ windows app] , a windows service is a good choice but you can also go for a interface less windows application [ not a console application]. Use Scheduled Tasks [Control Panel] to schedule this application on the time of your choice. Do what ever you want in this application viz.. updating database, sending emails, transformation, backup, merging or any other maintenance task.
Please note that, developing such application also require a logic for debugging [since you won't be having an interface ]. Also you need access and previleges on web server to actually install and schedule this appplication.
We are doing a similar thing in our application , therefore i suggested this.
You have include a single module in your application with a main method. No forms are needed.