It is widely acknowledged that any responsible modern-day organization will strive to protect its network against malware attacks. Each day brings on a spawning of increasingly sophisticated viruses, worms, spyware, Trojans, and all other kinds of malicious software which can ultimately lead to an organization's network being compromised or brought down. Private information can be inadvertently leaked, a company's network can crash; whatever the outcome, poor security strategies could equal disaster. Having a network that is connected to the Internet leaves you vulnerable to attack, but Internet access is an absolute necessity for most organizations, so the wise thing to do would be to have a decent web security package installed on your machines, preferably at the gateway.
There are several antivirus engines on the market and each product has its own heuristics, and subsequently its own particular strengths and weaknesses. It's impossible to claim any one as the best overall at any given time. It can never be predicted which antivirus lab will be the quickest to release an update providing protection against the next virus outbreak; it is often one company on one occasion and another one the next.
Web security can never be one hundred percent guaranteed at all times, but, there are ways to significantly minimize the risks. It is good and usual practice to use an antivirus engine to help protect your network, but it would naturally be much better to use several of them at once. Why is this? If, hypothetically speaking, your organization uses product A, and a new virus breaks out, it might be Lab A or Lab B, or any other antivirus lab, which releases an update the fastest. So the logical conclusion would be that, the more AV engines you make use of, the greater the likelihood of you nipping that attack in the bud.
This is one of the ways in which web security software can give you better peace of mind. Files which are downloaded on any of your company's computers can each be scanned using several engines, rather than just one, which could significantly reduce the time it will take to obtain the latest virus signatures, therefore diminishing the risk to your site by each new attack.
The long and short of it is this: you want the best security possible for your network, but it's not within anyone's power to predict where the next patch will come from. Rather than playing Russian roulette by sticking to one AV engine, adopt a web security package that will enable you to use several of them.