I'm running windows 10.....I've no doubt that Microsoft have their own security, but I've just got a thing about people who try to do everything ( jacks of all trades ) and end up doing everything averagely well. With security, I prefer a dedicated service; who concentrate on that alone...........as for rootkits.

https://support.avg.com/SupportArticleView?l=en_US&urlName=What-is-rootkit