Well, all I can say is this: I'm using Kaspersky Internet Security since beginning of 2009, and never changed. Meanwhile, I tested many security software, and still I do (I'm very interested in PC security) :BitDefender (good one), Norton(good one), F-Secure (good one), the new Comodo Internet Security (good one, besides freeware), Avira (excellent on detection the antivirus, probably the best one, but the security suite must be still improved a lot in many sector, starting from the firewall. At the moment, it simply can not be compared with Kaspersky one), and many others.
I can assure you at the moment there is nothing like Kaspersky available. Please, NOTE : I'm talking about Kaspersky Internet Security 2011, also known as KIS (last version is 11.0.2.556, soon will be available the first build of Kaspersky Internet Security 2012, now in beta testing) and not about Kaspersky Antivirus, known as KAV. Of course the anti-virus engine is same, but there is an absolutely big "GAP" between the 2 Kaspersky products.
KIS has got a lot of real time protection modules( e-mail, websites, phishing..), HIPS, an excellent firewall(probably the best one available at the moment, it doesn't matter free or shareware), geographical filter (introduced in 2011 version) that allow you to select additional checking for some country websites (for example Yemen, Iran, China..) or totally block the access. This feature can seem not so rilevant, but can be very useful, especially in case of some unwanted re-directing, antirootkit scanner, vulnerabilities scanner based on Secunia database and much more...
Besides all this security features, highly configurable, there are some very important security tools, such as Safe Run for Websites, Safe Run for Application, Virtual Keyboard Anti-Keylogger (absolutely great; everything is typed from there can not be "seen" from the O.S.,it doesn't matter what kind of info-stealing malware is stored in the machine. All happens like in a "separate", virtual O.S. and when you close the Safe Run or the Virtual Keyboard everything disappear, leaving no any traces in your PC. That's absolutely excellent if you have to introduce important info in a website, like in a on-line banking operation; of course if the website is a fake one you get warning at once).
well, there could be many other things to say. but then it could go too much technicals...
All I want to say is this: if you have to spend some money for security software (today is probably becoming increasingly necessary) my suggestion is 1, and only 1: Kaspersky Internet Security
Oh, last thing: I'm just a Kasperky customer, not a worker... and thanks to DOC for providing always interesting and useful info.