Windows systems are susceptible to viruses, and despite having the best antivirus installed on your machine its possible that your PC gets corrupted. If you are not a computer professional then a simple virus can also create havoc for your PC.
Its a best practice to save a restore point for your PC using Windows System Restore utility. Before changing any system settings you should always set a System Restore Point in order to make recovery easier in case of problems.
While Windows XP will set these points automatically at various times; setting a specific point can be useful if there are things you've done after Windows sets its automatic point that you want to keep. Recovery to a set System Restore Point can cause data loss from that point forward as that's the purpose of the restore point: to restore the system to a particular point in time. (The data and/or program may still be on the hard disk but the registry may no longer point to it if you restore to a point before installation of a program. This can cause problems accessing the data.)
To set a System Restore Point...
-> Open the Start menu
-> Open the Programs menu
-> Open the Accessories menu
-> Open the System Tools menu
-> Finally, start System Restore
Pick the option for setting a System Restore Point and click on the Next button
Fill in a name for the restore point so you can find it and click on the Create button
Click on the Close button when done
If you need to restore the system to a particular point or change the options Windows uses to set restore points use the System Restore tool as well.