Yes you do need to have some security software installed onto your computer but there are a number of reasons why you should select software that performs specific security tasks instead of installing one monolithic security suite.
While most security companies these days offer a security suite that supposedly includes everything you'd ever need as an alternative to their specialised security products, there are a number of reasons why selecting a security suite is likely to be the wrong alternative for your situation.
Just about all security companies started out specialising in one particular aspect of computer security. That area is the one they know the best because they have been working with it the longest. In order to expand that product into a security suite they have either bought a company that provided a product in a different area of security and somehow combined the two programs into one or they have written their own components to provide the other aspects to the security. Often they did both so as to provide half a dozen or more components within the suite.
The problem with this approach is that their suite has one or perhaps two good components that may be up there with the best products in that area of security but the rest of their suite is mediocre and while it might sort of do the job it doesn't do it as well as a stand alone product would do. Also since many aspects of computer security only allow you to run one program covering that aspect (since multiple programs will interfere with one another) you are making it more difficult for yourself if you decide that a particular component in the suite doesn't meet your requirements and that you need to replace that component with a different program.
It can be done though if you do find yourself in that situation. For example: while Kaspersky internet security suite will insist on the ZoneAlarm firewall being completely uninstalled before you can install the security suite, you can then completely disable the firewall in the security suite and reinstall the ZoneAlarm firewall.
Security suites are far less tollerant of other security software running on your computer than stand alone security component software is. While you can only have one firewall or antivirus program installed on your computer, many of the other aspects of security can work with multiple programs installed that are basically intended to provide the same protection. There is nothing to stop you having several antispyware programs installed on your computer as long as you don't try to run them at the same time. Unless of course you have a security suite in which case the security suite may insist on all other antispyware programs being removed from the computer.
Another reason why a security suite may not be the best choice is that you may not need all of the different aspects of security that it provides. In some cases installing a security product lessens the security of your system because it makes it look like you are protected when in fact you are not. I have seen suggestions that running a firewall to block outwards communication from your computer on a program by program basis is false security simply because most people do not understand well enough what the messages it pops up when a new program requests access and so they approve everything that asks for access. Doing this means that the firewall is effectively doing nothing since the person using the computer is going to approve any malware that requests access. They are just as secure as if they were not running a firewall at all but they think they are more secure because they are running one.
Most security suites these days come with a built in list of software considered to be safe for certain types of access. This is because most users don't know what software needs what level of access in order for it to function. You therefore end up with common software that you want to block being allowed access because it is common oftware and not so common software that your system relies on to function correctly being blocked simply because the suite doesn't recognise it. One security suite I looked at put almost all of the networking software that my network relies on to function into the restricted zone where the software couldn't do its job properly since the security suite was preventing it from doing what I had installed it to do. As that particular suite did not provide any easy way to change the zone that various programs are in the simplest solution was to turn off that component of the suite. Of course the same thing can happen with individual component products as well. One firewall I tried did not recognise the local network the way earlier versions of the same software had and so blocked all of the local networking software from running at all. Of course with individual components it is far easier to uninstall that software and replace it with something that does work if you can't figure out how to change the settings to fix it.
Using a security suite means that you limit yourself to what aspects of security that you are actually covering. When you determine that a particular aspect of the security suite is useless and turn it off you may not be able to install a replacement for that component. For example, turning off the spam filtering in your security suite may result in a huge reduction in te amount of spam reaching your inbox but the security suite may prevent your installing any other spam filtering software to try to reduce the amount of spam even further. Since many email programs have some sort of spam filtering built in you can easily have this exact situation happen if you have been using the email program for a while and have it reasonably well trained to recognise a lot of the spam and then the security suite spam filter comes along and tampers with all the spam so that your email program no longer recognises it as spam.
With individual component software you get to decide what security components you need. You can mix and match components from different companies so as to get products known to be amongst the best at doing what it is there to do and so have top class software covering all the aspects of security that you want covered instead of having top class sotware in one area and mediocre software for the rest as you often get with a security suite.
With independent component software when you start having problems with a particular component where the security company has updated it to work in a way that is incompatible with your system you can replace that component and continue running the same software for all your other security needs.
Over the years I have tried two security suites. The first of these provided excellent firewall protection but was nothing special in most of the other areas. The antivirus component of that suite tested files as you opened them and as I was deleting all the emails that might have contained viruses without opening them don't think I ever saw a virius alert out of that suite. The spyware component of the suite I never had enabled at all as I considered an alternate program to be far superior in that area. The second of the suites I tried gave me nothing but troulbe and within the first couple of weeks I had turned off everything in the suite with the exception of the antivirus and the firewall. With that antivirus it was scanning emails as they were being downloaded and the overall result of that was that the changes that the antivirus made to the infected messages meant that they all ended up in my inbox to be manually deleted instead of most of them being sent directly to the spam folder as had been happening before I installed the suite.
Make security much easier for yourself long term and avoid the use of security suites.
This article written by Stephen Chapman, Felgall Pty Ltd.