Very mixed opinions re MSE in the industry at the moment, mostly the consensus is it's barely worth what you pay for it... MSE is also not available for MS Windows 8 or 8.1 - it's been rolled into Windows Defender. It's definitely better than nothing, don't get me wrong. Avast on the other hand, is excellent AND the same price if you choose the free version. Malwarebytes is an excellent second line of defence and EVERYONE needs a backup.
Sorry to burst the bubble a little British Red, but a backup is only as good as the restore you can make from it - the vast majority of people never make one, the vast majority of those who do never make any attempt to test they can restore from the backup. Additionally there's plenty of malware which will survive a factory reset by writing either itself or persistence code to the restore partition having infected the bootloader of Windows or, less commonly the boot sector of the disc. A Google search for the terms 'Alureon' or 'TDSS' (both now a couple of years old, but the concept still holds) will demonstrate what I mean.
I could go on for hours and hours, I've even done it at partys (because I'm so interesting - 23 years in front line IT support will do that to you y'know), instead here are 5 basics that most people don't realize, or don't care to hear:
1. Make a backup copy of anything you cannot afford to lose. Do it now and test that you can restore from it. Then keep it disconnected (and remote) from your computer until such time as you need it. This is your disaster recovery point. Periodically update it by making another one when you've made some more stuff you cannot afford to lose. Rinse and repeat. Having more than one disaster recovery point is a good thing, not a waste of space - if you need advice on what to buy to use as disaster recovery media, drop me a pm.
2. Don't rely on security software to keep you safe. It's not the first line of defence, it's the safety net. See point 3 below.
3. The most important security setting IS NOT on the computer, it's in your head. Turn up the paranoia a notch, they're not out to get YOU, they're out to get ANYONE.
4. When you go scrumping, you don't carry a ladder to climb to the top of the tree. You grab what you can before parky sees you and run like hell. The same is true of most malware - don't be the low hanging fruit and you remove a significant portion of the risk. Essentially this boils down to keeping your software up to date - if the computer says there are updates available, do them straight away, it is trying to keep you safe.
5. If it, whatever it is, looks even slightly suspicious, avoid it. Verify attachments or links sent to you by email contacts or friends or family VIA ANOTHER MEDIUM (e.g. phone mum up when her Yahoo! account sends you a .zip file in the email 'I found this photo of you') before... wait I've not over stated this, ahem BEFORE you try to open it. Why via another medium? If you email them back and their account has been compromised then you're emailing the person who compromised the account, not the person you think you're emailing.
SOURCE: Err... me. I remove malware from people's computers for a living and have done so for a very long time.