Is windows defender good and effective as an antivirus?

I hear it's pretty good at detecting and defending systems, though i myself use Avast mainly because i would rather have an third party program protecting me rather then something that comes with the OS.

Thanks CDdude55 for your reply.I also prefer AVAST.But due to some unknown reason after installing avast all the network apps stop working(though I am connected to network).I have posted the problem in detail windows 8 forum of tom's hardware.I am yet to get an answer.
If you know the solution then please give a reply.

I've been using MSE for a couple years and never had a problem with virii infecting my machines. It's a good antivirus

Haven't tried the Windows 8 consumer preview, but it might be a problem that will be fixed with the retail release of the OS if someone can not find fix for it currently.

Post back here if you get an answer for the issue over there. It would help us if the issue arises form some here.

Thanks egilbe for sharing your experience.  

Thanks CDdude55 for your reply.  
I also have the same opinion of yours;it might be a problem of the OS.Hope it will be fixed in the final release.
Surely I will post if I can solve the problem.

I also use Windows Security Essentials, and ZERO problems.

It's Seamless, always works, and lightweight on resources. Best I've used, and I used to use Avast also.

Thanks dadof1hunter, for your reply.I am pleased to know that WINDOWS DEFENDER is a pretty good antivirus.  

I had the same issue earlier today. I tried turning off Windows Defender because I wanted to update my MSE (which I had installed immediately after downloading the Windows 8 Consumer Preview on the very first day it was available). I think that I was able to use MSE because I downloaded it so early on. It no longer allows me to install updates for MSE, even though it was installed. I turned off Windows Defender, and tried to update MSE to no avail. I then tried uninstalling MSE thinking that might fix the issue; no success. After this I tried turning Windows defender back on, and it kept saying that it was no longer monitoring my system. However, it would not let me open the program. I found no information on the internet on how to get Windows Defender working again and was forced to reinstall the Consumer Preview. I'm going with issues with the OS.

this is how to restart windows defender http://windows.microsoft.com/en-CA/windows7/Using-Windo...

Windows 8 Defender includes MSE, so you do not have to install MSE.

Defender is ok, but has been replaced by Microsoft Security Essentials.

I wish M$ would just get it over with and integrate the AV+firewall etc into one, with a nice light gui frontend.

  Hi Everybody
Today I Start Install Win 8
Keeping Windows Definder
As my Antivirus Program
I Hope   Its Going Will

Same here, I installed it out of curiosity and it is working well enough.
The OS hasn't slowed down at all and just made me feel comfortable having something to use for safe browsing.
Initializing Windows Media Center was a bit confusing initially (no pun intended).
I still need to install content packs for playing DVD's with it.
But I have been using it for a month as a Media center PC hooked up to my TV.
I watch Netflix, Hulu, Amazon Prime, Google Play fairly well. Although Amazon did have some playback audio & quality issues, the others work very well.
I was disappointed that Windows Mail won't let me use multiple email accounts, I liked the interface.
I installed Live Mail Desktop and it works decent as expected though.

Check AV Comparatives AV-Test and VB100 to see how it stacks up against the paid and non-paid competition.

i have never had any problems with windows defender or Microsoft security essentials, however have many problems with avira and avast. Windows defender has conflicts with 3rd party antivirus software. If running 3rd party u must disable windows defender.

A little late with the response  

*Looks at original post date*