If you know what you're doing and install Firefox with NoScript, Flashblock and Adblock as well as constantly update your system, you don't need to waste money on these products. I've had Windows computers for three years without any kind of anti-something software and never got a malware infection.
Save yourself some money and don't buy them.
1. If you do want one, get a free one like AVG. Pay-for ones aren't any more effective.
2. Depends on license terms. Look at their EULA.
3. 50% of real threats if you keep it updated? Really, installing Firefox and those add-ons will protect against 90%. No real studies have been done in either case, but beyond searching your system for known threats an AV program can't do much.
4. There are several, but again try to get free ones.
I would rather you used Mac OS X, BSD or Linux to be nearly 100% safe from threats, but no one ever bothers to try these things because Windows is all they know.
Ubuntu. Linux for human beings.
If you are interested in trying Ubuntu or Linux in general, PM me and I will answer your questions and help you install it if you wish.
