Beepster
With Windows 8 Windows Defender is built in
hmm... I hope they allow you to use other AVs if you wanted. MSE is fine for my DAW but Avast has been on my surfing computers for years and barring any major downfall likely always will be.
Also... Windows Defender is on my 7 systems but I think it's more of a firewall thingy. I'm a little confused. Is the Defender/MSE on 8 a special version of MSE or something? Surely it's not the standard MSE release if they changed the name.
I have no idea what the difference between MSE and Defender is, all I know is that the whole shebang was preinstalled with Windows 7 when I upgraded, certainly don't recall having to download anything extra. Maybe I'm wrong though.
Like you, I too used Avast for years because it seemed to be the best freeware AV out there. However, once I started to read about MSE being just as good as any other AV, I ditched Avast purely because it seemed wasteful to have it installed when a more OS-integrated AV was already there. To date, nothing has happened to make me think that Avast was a better AV.
There's an article here which stacks Avast against MSE in terms of computer impact, and the both scored almost the same, so I don't think there's going to be any kind of performance advantage with one over the other.
http://dottech.org/14151/...vs-avast-vs-avg/