To restore the system when it is up and running, go to "start". There select the tab "All programs", find them in the directory "Standard". You need the tab "Service", in which you can select one of the options, among them you will find "system Restore". Select this.
Windows Vista will prompt you which action you want to perform: restore an earlier state of the system or to create a savepoint. Select restore to an earlier state.
A window will open, which will feature a calendar and a list of all available restore points. It is better not to choose a long point, as they most likely will not be any important applications installed since that time. Choose a point closest to the time of any change, poorly affect the health of your system. Point must be earlier than these changes.
For cases when you cannot load the operating system, there are other methods to roll back to Windows Vista. You need to boot in safe mode. Restart or turn on the computer. A little earlier than it will start to boot the operating system, press F8 until you see boot menu. Then there is the string "Safe mode".
When I boot in safe mode as in normal case, select rollback system.
If you boot in safe mode does not work, press the re boot F8, this time select "last known good configuration". So your system will be put in the form that was last when managed to boot. Once the download has occurred, you can do a system rollback.
In order not to have problems with the points system rollback, disconnect the recovery service. So, whatever happens, you will have saved a healthy state of Windows Vista, and you can always return to any of them. If you are installing a program or driver that is particularly dubious, pre-can do to create a restore point.