Windows Defender is antispyware software that’s included with Windows and runs automatically when it’s turned on. Using antispyware software can help protect your computer against spyware and other potentially unwanted software.
If you buy another antispyware yourself ,you can disable windows defender in windows 7,below is a simpe guide about how to do it.
1.Launch windows defender from windows Control Panel
2.Click Tools on the window appears
3.Click Options in the next window
4.In the next window,select Administrator and uncheck Use this program ,then click Save
5.Done,a new window appear to notice you the windows defender has been turned off