Is Windows Defender Good Enough?

When you install Windows 10, you’ll have an antivirus program already running. Windows Defender comes built-in to Windows 10, and automatically scans programs you open, downloads new definitions from Windows Update, and provides an interface you can use for in-depth scans. Best of all, it doesn’t slow down your system, and mostly stays out of your way—which we can’t say about most other antivirus programs.
For a short while, Microsoft’s antivirus fell behind the others when it came to comparative antivirus software tests—way behind. It was bad enough that we recommended something else, but it’s since bounced back, and now provides very good protection.

So in short, yes: Windows Defender is good enough (as long as you couple it with a good anti-malware program, as we mentioned above—more on that in a minute).