For basic needs you can use the MS Backup application included with XP. In reality that app is provided by Veritas who was once famous for their Veritas backup exec and Netbackup products. It's basic but you can recover an entire system with it in a pinch.
If you just want to do file copies on a schedule get Robocopy from the XP resource kit available at Microsoft.com. Build a simple script and use the task scheduler to run it when you want.
Beyond this are commercial solutions that you can look into, however they can become cost prohibitive.