unfortunately it is one of the poor elements of windows hosting in that most LAMP hosts allow you to set up cron jobs but most windows shared hosts dont allow you to set up scheduled tasks or have some poor interpretation of them.
Okayyyyyy ... Revised solution: Get a Linux hosting with cron-jobs. Use curl to periodically invoke a script on your Windows server. LOL! If Task Scheduler can not be used and another Linux server isn't really what is wanted, the link below shows a possible workaround - with quite some pitfalls! http://www.angrycoder.com/article.aspx?cid=5&y=2003&m=4&d=11
Or if you leave your home PC on 24/7 just set up a scheduled task there to connect to the page with the code required... again a bit messy but is a viable solution.