With less than two weeks to go before the NCAA March Madness tournament begins, a warning is going out for IT managers to prepare for one of the riskiest times of the year.

Security experts say the highly anticipated tournament is more than a significant productivity drain. It also clogs company bandwidth and opens networks up to the threat posed by large amounts of malware. The series of games, which are played during the day and during the work week, are worse for networks, and the IT managers who run them, than even the Super Bowl and the World Series, says Steve Kelley, a senior director at Websense.

"We've been monitoring over the past several years the way employees are using the Internet, and March Madness has been a big issue," says Kelley. "It's about more than wasting time. It's about potentially putting the company at risk."

Here's the problem: The games generate an enormous amount of excitement and buzz -- offline and on. Add to that the fact that the games are played during the normal work day. That means sports enthusiasts, and there are a lot of them out there, are watching real-time feeds of scores and standings on their desktops and laptops. They're watching streaming video of live games when no one is watching them. They're working on their final four predictions. And they're probably even placing bets at online gaming sites, which are notoriously riddled with malware.

Last March, Nielsen's NetRatings reported that CBS Sportsline.com saw daily traffic increase by 21% on the first day of March Madness. And according to information from St. Bernard Software, more people visited sports sites at work than they did at home, with at-work traffic to NCAA sites attracting nearly 5.9 million unique visitors, versus 4.8 million unique visitors at home.

Challenger, Gray & Christmas, a global outplacement firm, estimates that for every 13.5 minutes workers spend on the Internet watching March Madness games, the cost to the nation's employers in lost wages exceeds $237 million.