The numbers say it all: In 2009, there were 148,000 zombie computers (spammers, botnets, etc.) created per day, over 2.6 million known malicious code threats at the start of 2009, and by the end of the year, nearly 1 million new ones were created. In other words, to quote the illustrious Stewart Baker: "[The security threat] is worse than we even thought."
and some other numbers
Congress and other government agencies are under a cyber attack an average of 1.8 billion times a month, a number that has been growing exponentially since President Barack Obama took office.
In 2008, security events caused by vectors including worms, Trojan horses and spybots averaged 8 million hits per month. That number skyrocketed to 1.6 billion in 2009 and climbed to 1.8 billion this year, according to Senate Sergeant-at-Arms Terrance Gainer.
The Senate Security Operations Center alone receives 13.9 million of those attempts per day.
Just try to imagine those numbers. Even if only 1% are targeted zero-day very genious attacks, it makes for hundreds of attacks to probe and stop manually.
If you don't have a budget and you have important data you just close down, limit access and block everything you can on a whitelist basis.There is no way any securityproduct will stop all of this all the time everywhere.