I have two questions:

1. In referance to your comment about not trusting Microsoft for AV software, who more then Microsoft has more of a vested interest in keeping your Windows machine running as well as possible?

2. What is it you think that Microsoft is going to do to you if they know more about you or your system? Do you think that they are going to send out the black helicopters? If you want ot be paranoid, fear the government, not Microsoft.

I installed MSE and like it. The installation itself was a breeze, the update was fast, the Quick Scan took about six minutes, and the Full Scan took about 40 minutes. I'm not concerned about it being slow, because scans will usually run automatically in the wee hours while my computer is idle.

MSE didn't find any viruses, which is probably because it's relieving from duty the excellent NOD32. The difference between the two seems to be that MSE is lighter on digital and financial resources. If a problem arises, I can always go back to NOD32. So far, I'm confident that won't be necessary.

I too had a twinge of concern about this MS product phoning home, but that could also happen with Windows Updates or via some other back door. If we fear MS that much, it's simply time to switch to Linux.

If MSE slows your computer then it's most probably due to a lack of RAM. I had these effects at first despite a pretty fast P4 processor, but then realised that the 512MB of RAM installed by the computer manufacturer were probably not enough when I often have many webpages open, am recording sound and emailing etc. at the same time. MSE had simply highlighted the fact that I was really pushing the limits. I installed an extra 2 GB of RAM and since then MSE has run unnoticed (and many other things a lot faster of course). When a full scan doesn't interfere with what you are doing who cares how long it takes? MSE certainly seems both quicker and more thorough than Windows Defender. It hasn't found anything yet, but then I already had AntiVir and Spyware Doctor.

I was running Avira free as well but my thoughts are Microsoft as needed to do something about security for awhile. I think a full program designed by the makers of my os; giving it a try seemed to make since. And I've been really pleased.