I personally think the best was Norton A/V corporate edition... but the problem with it is it doesn't work on vista/7 or any 64bit O/S.
They do have new versions of it out that does support the newer Microsoft platforms, but I can't vouch for any of it. The version I used to use (still do on my netbook running XPHome) was great, low maintenance, and used little resources.
This is the exact opposite of their "home" products which are, in my opinion, more dangerous than most of the junk they are supposed to protect you from.
LLama and Skuzzy are right.. a virus can do some nasty stuff, and many can't even yet be detected, BUT I still don't feel viruses/worms are nearly as much of a threat as adware/spyware. These programs are often not even scanned by A/V software, and are often installed WITH YOUR PERMISSION without you even knowing it. Simply put, if it contains "ASK.COM" or just about any kind of "TOOLBAR" then it's just going to eat away at your system resources, causing problems and giving you nothing in return (while making their publishers money). Even yahoo and google are guilty of these practices. On one hand it's hard to blame them.. they provide services (for the most part) free, and have to make money somewhere... but on the other hand there's got to be a better, more honest way for them to approach this.
Sometimes this stuff gets installed downright secretly, but more often you allow it to happen. I've noticed a growing trend for software (mostly freeware but even some retail boxes) that hide an option during the installation process that you'll easily ignore if you're not looking for it. I think it's Glary Utilities... nice little program.. but during the installation routine it will show your EULA and at the bottom have a checkbox (already checked for you) that says "I agree to the terms of the EULA and wish to install the ASK.COM toolbar and system utilities software". If you're not paying attention and click NEXT then they gotcha! If you DO pay attention, it would be easy to think that you HAVE to install the extra software in conjunction with the original software so you leave it checked anyway. *BUT* you can uncheck it and then proceed safely. I should note that if you actually take the time to read the EULA, you'll see that it is for the ASK.COM and other junk, and when you click NEXT then it shows another EULA for the actual software.
About once every couple of months I'm at my dad's house and I go through and clean up his computer. Every time, he has about five or six toolbars running (ask.com, google, yahoo, AIM, and god only knows what else)... some of which block a lot of his browsing real estate, and a lot that don't. I keep telling him not to install these, be he swears the yahoo one is required for him to access his email, even though I showed him otherwise.
My mom back when we still talked to each other, would REALLY fubar up her system and about once ever few months I would make her back up anything she wanted to keep onto a flash drive, and then just restore it from an image I made. I never even bothered with windows updates or any of that.. just set it to automatic and made her deal with it. No matter how clean or perfectly configured her system was when I was done, she'd manage to fubar it within a few months. About six months after we stopped talking, she gave her computer to my brother and spent almost three grand on one for her. I fixed it up for him (restored from image, updates, etc) and he's been using it for over a year now trouble free... and it's not even that old! I feel sorry for Best Buy's tech support (or whoever she bought it from) as they'll be getting a call from her about once a week!
My point of this novel is that no matter how well protected your system is, and how great the software you run is, it's still up to YOU to keep it clean. I think some common sense practicing safe computing habits (including configuring a good NAT firewall and browser settings) with NO protection whatsoever is many many times more effective than the opposite.
A good practice is to start with a nice fresh install.. put in all the windows updates and hardware drivers.. and then make a disk image. There are many types of software out there that will do this (and some are free!) and with TB hard drives being as cheap and common as they are these days, there really is no excuse for not doing this. If you have the hard drive space, go ahead and install whatever software you want before the image is made. If space is tight, you can image before installing everything (but then you'll have to install everything after restoring in the future). I was able to fit everything on my g/f's father's computer on an image on a single DVD. After this step, make sure you keep backups of any documents or game settings folders and other things you don't want to lose. You can do this to a flash drive, an external hard drive, CD/DVD, online storage... whatever floats your boat!
Then if/when things go south all you have to do is restore your image, install whatever software, and copy your documents back. It really doesn't take that long, and doing this ALMOST removes the need for AV software altogether.
Now if you have critical documents (such as top secret company/government stuff.. or financial records.. or whatnot) then this ups the bar a bit higher.. but people who use their systems in this kind of manner usually already know how to take the proper precautions. I'd be willing to bet that more than 99% of people would lose nothing more than memories if their computer were to get compromised... and that's the easiest stuff in the world to keep backed up.
So.. in a nutshell:
- If someone wants in your computer specifically, they're going to get in no matter what you do... luckily this doesn't happen very often to the average Joe Schmoe
- While random attacks DO happen, very basic precautions will prevent over 99.9% of these types of things
- Back up anything you don't want to lose
- Don't keep anything solely on your computer that you can't afford to lose
- There is no need to be afraid of the internet, so long as you use common sense
- Sometimes A/V applications cause more problems than the malware it is designed to protect you from! (Kind of like medicines where the side effects are ten times worse than the original disease!)