What OS are you using?
As far as AV software goes, I'd suggest Forticlient, but you'll need to set it up to not block all of the content you regularly use. Or Avira, but you'll have to deal with pop ups once a day.
Also ESET's software is pretty fantastic if you're going paid.
Other than that break your wife's cousins knees.
Let me clear things up... There is a free version and a paid version.
The paid version can be managed by a FortiGate (prior to 5.4.1) or by EMS. This version has the same features as the free version but is centrally managed.
The free version is available at http://www.forticlient.com, its free and you can use it either for AV or VPN, or both - there is a install option for it to be VPN only if you have a preferred AV product already.
MSE and SpyBot are a great quick way to secure a system for free. SpyBot's Immunize and TeaTimer functions are great.
You can go one better and use FortiGate's FortiClient, which is free (they make their money on their network gear, into which FortiClient can hook) and we use it for endpoint security at work. In additional to anti-malware it can also block known bad websites, and this list gets updated by the client when it updates things like definitions. It will also perform a TeaTimer-esque function by watching for file access and verifying files when they arrive from the Internet.
MalwareBytes (free) isn't going to secure your computer but it's decent scrubware.