An old thread, but still a goodie.
I'll add my two cents' worth.
I've been using computers since the days of the Apple II series, and PCs since the early 1990s. These days my home network has two PCs, A Synology NAS (Network Attached Storage) device, an Android tablet, a first-generation Kindle Fire (which is essentially another Android tablet), and a few Internet-Of-Things devices. I use Bitdefender Total Security 2015 on both PCs, and Synology's antivirus software on the NAS. My router has a name other than the default, and of course I changed the password as well. The Android tablets and my phone run their own security software, but they're irrelevant to this discussion.
Every security option is enabled on each of these devices/applications, and the security applications are updated both automatically and on-demand whenever I hear of something new in the way of malware.
The Bitdefender suite does more than just antivirus protection. One feature I especially like is the way it alerts, blocks and logs suspicious or has potentially malicious code on any site I go to, and I'm amazed at how many reputable sites do harbor such code. The code may be part of an ad running on a page, and I get a warning even if I never go anywhere near the ad; it may be nothing more than spyware or adware, but a look at the log tells me it is/was there ... and that it was blocked.
In addition I run a couple of stand-alone antimalware programs (Malwarebytes and Ad-Aware) on both computers at least once a week. This may be overkill, since I haven't seen anything reported by either program since I've been using Bitdefender, but I'd rather be safe than sorry.
I also run CCleaner (a nice utility for removing "garbage" files and Registry entries) once a week, and do a few other things to keep my computers running smoothly.
Why do I do all this?
Several months ago, I began seeing attempted thefts from my checking account, using the information from my debit cards. Whoever was behind it was good, and apparently they were getting the information from my computers -- in once case, they had the info for a brand-new debit card within 24 hours of my activating it, before I had used it anywhere except for one internet purchase. (Unfortunately, I began a weekend trip the very next day. My bank caught the attempted fraud and cancelled my card while I was on the road. Good thing I had sufficient cash ... and another card ... to get back home.) Until that particular attack I had been suspecting a skimmer had been mounted on the credit card reader at a gas station or carwash -- I have found a couple of skimmers other places, but the thieves are getting better at disguising and mounting them.
Until then I had been relying on Windows Defender and Windows Firewall, free and included with Windows 8.1. I'm not saying either Microsoft program allowed the thief/thieves to gain access to my information, but I decided then and there to start using something that the experts recommended. In my research I learned that Windows Defender (and Microsoft Security Essentials for Windows 7) were pretty good, but better applications were better. After comparing five or six tech-related Websites/magazines I respect, I settled on Bitdefender as the overall best for my purposes; I chose the Total Security version, because it provides the most comprehensive protection. I am not saying Bitdefender is the absolute best antimalware suite, just that it works for me.
And sometimes I reboot into Linux when I'm shopping, although it's a bit of a pain. Neither of my printers (a Brother laser and Epson all-in-one inkjet) are automagically supported by any Linux distro I've tried, and I change distros fairly often just to see what's new, so I usually have to save the receipt and then reboot into Windows to print a copy.
I have not had one computer-security problem since then, and now my money stays in the bank until I authorize its removal; thanks to my bank, the local police department and Lifelock, I even got back $1300 from purchases I didn't make. But just to be safe, now all my online purchases are made using either a reloadable debit card (which I load just before I make a purchase) or a credit card (which offers additional protections and is used for larger purchases).
Maybe you don't think you're important enough for thieves to target. I didn't either. Maybe you never make online purchases, or you've just been lucky so far. But if you buy anything (such as cigars!) online and you don't take precautions, sooner or later someone is likely to gain access to your financial information. Even Macs and Linux systems are potentially vulnerable -- for that matter, I'm told a lot of routers are too.
Please learn from my experience; I got most of my money back, but not all of it -- the thieves made too many small purchases from too many different vendors, some of them overseas. And filing reports with your bank and the local police can be both time-consuming and frustrating.