Windows equivalent to cron?

"Scheduled Tasks:

With Scheduled Tasks, you can schedule any script, program, or document to run at a time that is most convenient for you. Scheduled Tasks starts every time that you start Windows XP and runs in the background, and it starts each task that you schedule at the time that you specify when you create the task.

Also, you should check out this article from Lifehacker on using Scheduled Tasks. It gives examples for Defragging your computer, restarting your computer, and opening Firefox when at startup with a set of websites"

Windows task scheduler. Support article for scheduling tasks on XP.