I’ve been dogfooding Microsoft Security Essentials for quite awhile now and recommend it to everyone one I know. Download it free today here.
Did I mention that it is free-as-in-beer?
Event though I use remote assistance and PSR to help friends and family troubleshoot their machines, step 1 on my list? Install MSE.
Help and Support: Help and how-to guides
Installation Video : See just how easy it is
And it is free, and auto-updating. And free.