In addition to creating regular restore points at 24-hour intervals, System Restore creates restore points when you do any of the following:
Install an unsigned third-party driver. When you install an unsigned driver, XP displays a warning message. If you continue anyway (and who doesn't?), the system creates a restore point before continuing installation. So just ignore any warnings. XP's got your back.
Install an application using an installer that's compatible with System Restore. Applications that use the Windows Installer (.msi files) and InstallShield Professional 6.1 (a cornflower blue interface with little arrows) or later are included in this category.
Install a Windows Update update or a patch. Windows creates a restore point automatically when you download and install an update using Windows Update.
Restore a prior configuration using the System Restore. Each time you run System Restore, System Restore creates a new restore point so that you can undo the restore, as mentioned earlier.
Restore data from a backup set created with the Windows XP Backup Utility program. If the restoration of the backed-up files creates problems, you can reverse the effects using System Restore.
Plus, you can modify the default restore interval so that it sets restore points either more often or less so. Just follow these steps:
Open the Registry Editor and locate the HKLM\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\SystemRestore key.
Change the RPGlobalInterval value from its default setting of 86,400 (a value of seconds, which, to save you a trip to your calculator, comes out to 24 hours). Cut it in half, to 43,200 for example, to take a System Restore snapshot twice a day. Double it for snapshots every other day, and so on.
Note that you have only changed the scheduled restore points. The automatic snapshots (installing new programs, drivers, etc.) will still take place.