Where to start in Microsoft Security?

I recommend browsing to https://www.microsoft.com/technet/security/default.mspx as a top level page to find out what's important with security from a technical perspective.

There's a link titled "Want less Technical Information" which links to the consumer oriented advice which includes nice concise guidance including short videos by real people (OK they're actors/actresses - at least they're not techies) explaining how to avoid Malware, Phishing, Pharming, Spam et al. I find this site useful to point family and friends to rather than explaining it AGAIN myself :-)