It really depends on your uses and habits as to what level of security you should have.. I consider Basic Security needed for those that only surf a couple sites daily, check their emails ect.. This would consist of a decent AV, an Ad blocker, and a couple different forms of back up of system and personal files... The chances of getting hit with an infection just lightly surfing are very slim, and the back ups would be your fail safe should the AV not be able to catch anything you may encounter. This type of set up should be recommended to novices as a bare minimum.
Now if you use your system to test in a VM, or you game, visit dodgy sites, constantly research in unknown territory, then you may want to consider layering that systems security. I have been testing the combo of anti executable software with a decent AV as well as a custom set ad blocker. I game and use Team Speak, and research almost non stop when online in unknown areas and every once in a while use a VM for testing applications and malware.. Because it is a gaming machine, i want to keep my config as light as possible, with the least amount of intrusive pop ups from the security, while maintaining a hardened system at the same time. This form of set up im testing for myself i would consider Moderate Security, and is indeed still backed up by system and personal external backups..
Anything more then this, i would consider Extreme Security, and only needed in a business environment, corporation's ect, where the chances are you would be more seriously targeted.
