Note that you need to have at least 300MB of disk space free and the hard drive must be 1GB or larger in order for Vista to create a restore point.
Follow these steps to create a restore point.
1) Click on the Start button and then click on Control Panel.
2) Go to System and Maintenance, System, System Protection
3) Click on the “Create…” button on the System Properties, System Protection Tab.
4) Enter a brief description – something that will help you remember the state of your computer at the time of the restore point. Click Create.
5) Your first restore point will take a few minutes to create. Subsequent restore points should be created quicker. Click OK on the dialog box when it appears stating that the restore point had been created.