Windows Defender is a pretty good free antispyware application that is available for Windows XP and is part of Windows Vista. Here’s how to install or uninstall Windows Defender in XP and Vista.

Windows Defender in XP

You can download and install Windows Defender free of charge on the Windows Defender website ^[1].

You’d uninstall Windows Defender just like any other program in Windows XP.

Windows Defender in Vista

Windows Defender is built into Windows Vista and is activated and running by default unless another antivirus software has deactivated it or you choose not to use it during installation.

Turn Windows Defender On (install)

1. Open Windows Defender by clicking the Start orb, select All Programs, and the click Windows Defender.
2. Click Turn on and open Windows Defender to activate it.

   ^[2]

If you don’t have another antispyware software package running the Windows Security Center will nag you with a balloon warning at the bottom right of your screen. You can click that balloon and then click Turn on now next to Spyware and other malware protection to turn Windows Defender back on.

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Turn Windows Defender Off (uninstall)

1. Open Windows Defender by clicking the Start orb, select All Programs, and the click Windows Defender.
2. Click Tools at the top of Windows Defender.
3. Click Options.
4. Scroll down all the way to the bottom and uncheck Use Windows Defender under Administrative options.

   ^[4]

You can turn Windows Defender off instead of uninstalling it just like this in Windows XP also.