Maybe, this wiki at MS will help:
Windows Defender on Windows 8 - Introduction and Frequently Asked Questions
It, also, answers quite a few other questions that some people have.
A couple of quotes from the wiki page.
Quote:
|
If you install a third-party anti-malware product, WD will be disabled. If you [properly] uninstall a third-party product, WD will be enabled.
|
Quote:
|
However, you can have an on-demand scanner, such as Malwarebytes, installed. Malwarebytes offers two different scanners – one on-demand (free), and one real-time (paid). The on-demand scanner does not conflict with WD’s real-time scanning. Some users consider having one real-time product (e.g. WD) and an on-demand product (e.g. Malwarebytes (free)) a good combination on their system.
|