Microsoft Defender works well at keeping you safe from various security threats, though certain situations might call for you to disable it.

Unable to turn on or off real-time protection in Windows Defender? Check these GPEDIT and REGEDIT settings and disable other antivirus apps.

If you'd like to disable Windows Defender in Vista—perhaps you've got another spyware system that works better— tech blog Nuts and Milk has a dead simple tutorial on how to accomplish this ...