Definitely go for MSE. I use it on all the PCs in my home network. It's never given me any trouble. The scan times are fast, updates are regular and the detection rates are AWESOME!
I don't know why AVG is still popular, go to cnet downloads and it's still NO1 when it's complete crap. It's been crap since 2 years ago when it couldn't delete the 'autorun' virus (was a real pain) and it is still crap now, avast as well.