Since Win7 went final last year, I migrated all my systems to MSE and have absolutely no regrets. Independent testing at the major certification labs has proven MSE is just as capable, and more so in many areas, as ALL the others, free or paid. So providing the expected protection is not an issue with MSE. Therefore, it comes downs to ease of use.
What I really like about MSE is (1) no bloat - it does not hog system resources in terms of CPU cycles, RAM or disk space. (2) The installation routine does not try to "
foist" a bunch of unwanted, often intrusive programs (or toolbars) onto my drive. (3) Simple to use - no extra "features" I don't need.
I also use Windows Firewall and IE8 and I keep my systems patched and updated with the latest security updates. And all my systems are behind a router. I run MBAM for supplemental/manual scans, and so far, every scan has been clean.
It is important to note that Microsoft tried to get into the anti-malware business with XP but Norton, McAfee, CA, and the other big AV makers went crying to Congress and the EU complaining that MS was trying rule the world and push them out of business. They claimed it was their job to rid the world of malware. We see how well that went!
But Congress and the EU were out to ensure MS did not create a monopoly so they blocked Microsoft's efforts to make XP more secure! Microsoft's mistake was they tried to integrate the AV into the OS, instead of offering it on the side as they do now with MSE.
What is important to remember is that Symantec/Norton, McAfee, CA, Trend Micro, and all these for-profit anti-malware makers have absolutely
ZERO incentive to rid the world of malware! If there were no malware, they would go out of business.
Microsoft, on the other hand, has a HUGE incentive to rid the world of malware!
Malware is caused by badguys free to do what they want because our elected officials (to include Congress, the EU, and the UN) refuse to fund to enforce even the existing laws. Yet, Microsoft bashers and the biased IT media (and in turn, naive users) constantly blame Microsoft and they, rightfully so, are tired of being blamed for a situation they did not create.