System Security is always a concern of PC users. Windows 10 provides you in-built protection from viruses and malware threats. In general, if you are using latest Windows 10 updates, you don't need to spend on another antivirus program for normal home usages.
Along with Windows 10 Creators Update, Microsoft is going one more step ahead to secure your PC further with a comprehensive dashboard 'Windows Defender Security Center'.
Windows 10 updates comes as Windows update service, but in case if you have downloaded the ISO image of the Windows 10 installation media, you might want to create a bootable USB device from it for fresh installation.