From the Mailbag

Ash and Julie:

I strongly advise you to pay for quality antivirus protection. PCMag recently reviewed Windows Defender and rated it 2.5 out of 5 stars (FAIR). However, based on my experience in the field, that review is generous at best. Simply put, Windows Defender sucks. Microsoft lacks both the expertise and the incentive to develop it properly. It is only marginally better than nothing.

If you are willing/able to pay then get ESET NOD32 Antivirus. If you are unwilling/unable then use a decent free antivirus like Avira AntiVir or Bitdefender. I would not rely on Windows Defender unless I absolutely, positively had no other choice . . . and even then only for so long as I had to.