I've heard of a piece of hardware which some people use in order to restore their computer to an earlier time ( a bit like system restore). Someone told me that it is more effective than using system restore in XP. Does anyone have any experience using this piece of hardware? How much do they cost? How effective are they? How many restore points can you save on your pc?

Try this software. It's good and free.

The only hardware solution that I am aware of...

CenturionGuard® is designed with a unique patented technology that has withstood the test of time in school and university classrooms and labs located throughout the world. CenturionGuard® uses a lock and key to enable and disable security protection.

Users can manipulate the desktop, install software, change settings, and download potentially harmful files from the Internet! No worries, a simple reboot of the computer restores it back to your defined configuration without the risk of probable harm from the user's session. CenturionGuard® simply wipes the session changes free leaving the computer like new.

FYI: I am uncertain whether this device is still available or not. I cannot seem to locate a price for it anywhere. (I seem to recall that it was $69USD at one time but please don't quote me on that.)

Available for Windows 95/98/Me/NT/2000/XP