[h=1]Got Windows 8 or Windows RT?[/h]Windows Defender for Windows 8 and Windows RT provides the same level of protection against malware as Microsoft Security Essentials. You can't use Microsoft Security Essentials with Windows 8, but you don't need to — Windows Defender is already included and ready to go. But if you’re looking to protect a PC with an older version of Windows, you can use Microsoft Security Essentials to help guard against viruses, spyware, and other malicious software. It provides free* real-time protection for your home or small business PCs.
Windows Defender IS MSE in an upgraded format for Win 8. If you look you will see MSE is at V4XXX, or at least it was when I last used Win 7. WD in Win 8 is at V6XXX. It uses the same AV engine, but at an Upgraded level.
In my opinion, whether you are a conspirator or not, unless Microsoft helps fund various malware security companies that develop for other third party AV's, they may want to try and break the security of Windows Defender, because they don't want everybody to believe in the protection given by the built in software that Microsoft would provide. (Even though Microsoft does have the best resources for retrieving samples of viruses to help make their protection better, and they do, do a good job of this in my opinion.)
They wouldn't make any money if nobody was using their products...
So if they had the ambition to join with Microsoft to help improve Windows security, there may not be as much competition going on. Until something like that happens though, it'll be every AV for themselves, like it has been for a while.
If you look at the good side of things though, this almost makes these 'bad people', bug finders, for helping raise awareness about, and improve, the security of a Windows OS.
So, from what I know personally about security, and Mark Russinovich is one of my biggest influences for what I know today, is that you still have to have vigilance when doing things on your computer. You can't put 100% full trust into these programs to help you prevent getting an infection on your computer, because there's probably someone at all times of the day trying to bypass certain security measures, for the antivirus you are using.
Best thing you can do, is to start to recognize the tell-tale signs. It's a proven fact that the majority of today's viruses are actually caught, by socially engineered malware. In other words, you get tricked, and you end up installing the virus yourself on your own PC...
Cat and mouse game.
The scary thing? Now we're starting to fool around with viruses that can go out and get remote access control to the computers that control predator drones. So unless this executed code knows that it's doing, somewhere in the world could be in a bit of danger!