What would be the best anti-virus software to match with Windows 8?
My personal favourite is ESET Smart Security. Though that's personal preference. As long as you go with one of the big boys (ESET, Norton, BitDefender, Kaspersky) you should be fine. They're all good, so its more a matter of taste than anything else.
I have been using bitdefender for a couple of years now. Much less of a resource hog compared to Norton. You also don't have to worry about keeping an eye on how often it is doing system backups.
I would highly recommend Bitdefender. Ranked #1 by so many review sites and it's one of the least expensive. If you don't want to pay, go with AVG or Avira. Reviews: http://anti-virus-software-review.toptenreviews.com/best-antivirus-software-for-windows-8/ AVG download: http://free.avg.com/us-en/homepage Avira download: http://www.avira.com/en/avira-free-antivirus
For windows 8 you should use the Microsoft Windows Defender. It works and it is free. I mean what is better than free?