And you should know by now, after all these years, about how I feel about paying for software. I don't think anyone should have to pay for a decent anti virus program. That was the same complaint to Microsoft before MSE came out, and Microsoft even got that program wrong. Why pay good money to cover holes in Windows programming?
Microsoft did nothing wrong with MSE, and before you point me to any article showing a low detection-rate etc. let me explain. Detection-rates among AV programs will vary from month-to-month. As I have now stated numerous times on these forums, I never use third-party software (AV or Firewall software) for protection. The best protection your system will ever have is for you the user to use it from a 'least privilege' perspective. Any third-party program will only ever be able to provide adequate protection to your system when compared to 'least privilege' computing. While securing one's system through 'least privilege' is preferable, I do recommend finding a third-party program or two for a second-opinon on overall system protection/health.
To that end I recommend doing the following. Since no 'real-time-scanner' can/will protect you from yourself on your system better than 'least privilege' I also weed out the programs that seem too focused on real-time 'protection' and instead get programs that focus on on-demand scanning (second opinion).
I suggested the following software a year or so ago in an AV thread started by Doc but here are some of the same recommendations again.
1. Hitman Pro (www.surfright.nl) - One of the fastest on-demand scanners I have ever used. (It uses the cloud to connect to 5 scanning/detection engines and a few years back was one of the only scanners that properly cleaned systems of the google-redirect etc.
2. Emsisoft Antimalware (www.emsisoft.com) - One of the most aggressive/deep scanning AV programs I have found to date. While the program does have a seemingly robust real-time aspect, I find the on-demand scanner one of the best.
3. MS Malicious Software Removal Tool I use if the first two on the list found and removed something. Of course one should run it in advanced/complete mode, and not the default 'fast scan'.
4. MSE (Microsoft Security Essentials) is a decent program in my view for what it does. It is light on resources (too many AV programs that offer real-time protection put a stranglehold on your system resources and to me that is a shitty tradeoff) and when combined with 'least privilege' computing is as much as the average person requires.