AV product reviews for the new Windows 8.1 operating system were highlighted in PC Magazine recently

http://securitywatch.pcmag.com/security-software/319941-antivirus-products-show-off-under-windows-8-1

http://securitywatch.pcmag.com/reviews/antivirus

http://www.pcmag.com/category2/0,2806,1639159,00.asp

QUOTE: In November’s edition of this report, Kaspersky managed a trifecta: six of six possible points in all three categories. Note that testing lab AV-Comparatives named Kaspersky their product of the year for 2013. Kaspersky remains at the top in the latest report, joined by Bitdefender. Bitdefender’s improved performance score pulled its total up to a perfect 18 points. Avira pulled its protection score up from 4.5 points to 6.0, putting it in second place overall with 17.5 points. Products from Qihoo and F-Secure tied for third, with 16.5 points total.