zeyuanfu :
I personally use Microsoft Security Essentials and Windows Defender as:
1, It's free (I don't feel like paying 50$ for something that slows down my PC)
2, It uses only a bit of RAM and CPU usage compared to other AVs (cough cough Bitdefender)
3, Come on, they were developed by Microsoft, who also developed Windows. They can only be great
I test AV software on older hardware, and Bitdefender does NOT use a lot of resources. Even with 24/7 file sharing, and streaming 1080p videos on a slow connection, with a low-end GPU, I've not notice it get in the way of anything performance-wise. I also don't game, so that could be one thing that people might notice a problem with; however, I've not had any AV wares cause a significant problem with gaming performance in the past (and I've used some heavy software too).
As far as Windows Defender... Microsoft does very little to protect your computer, so it's a trade off. I would rather run with zero-protection than with WD in the background. I just don't trust Microsoft, as their reputation is ruined; and they do not seem to value security in any way. In fact, there was a
European Parliament hearing where Christian Engström (member of Paliament for Sweden until July, 2014) and Nils Torvalds (father of Linus Torvalds, and a member of Parliament for Finland) were asking questions to a representative of Microsoft. When asked if the NSA had talked to Microsoft about installing a back door into Windows, the rep attempted to make it a point to dispel any 'myths' that might have been out there about Microsoft having back doors in their software. The way the ordeal occurred, it seemed like the rep's job was to end all speculation by insisting Microsoft was not doing deals with the NSA, or that there were any "back doors." While I already am sceptical of them, the way it was handled seemed like a guilty child trying to hide something. Obviously, this isn't "proof" of anything; however, it is showing that the company has been under heavy scrutiny by many; and they haven't earned too much trust. When a company has many speculated bugs by software engineers (based on previously found bugs), operates with closed-source software, and has a poor reputation with the programming/hacking industry in general... it's probably not very wise to trust your computer security with Microsoft.
Also, we have posted the same link, numerous times in this thread, to an independent research group: AV-Comparatives. If you looked at some of their charts, they compare WSE to current AV wares on the market. According to their testing, MSE catches about 85% of infections in real-world testing. MSE also scores a 7.3/20 on performance impact (higher scores mean more resource demanding), whereas Bitdefender and Kaspersky both scored a tiny 1.2/20, and Avast even came in at 6.2/20. Still think MSE takes up more resources than Bitdefender? This is from independent testing done by a non-profit group, and the results are documented. Do you have any conflicting evidence? If so, please share it.
Huang Ray- I've said it countless times... if you're only using AV software as protection, and you take no other security measures, there is nothing that will be "enough" for your protection. It is "enough" for a substantial AV software? Yes, and I've provided a very long post explaining why on the previous page.