When it comes to data security, peace of mind is fleeting at best. Just when you've sequestered your precious information behind the highest wall money can buy, some malevolent hacker inevitably figures out a way to undermine your plan. Or one of your software vendors announces a security flaw that needs immediate patching.

Perhaps that explains why security spending is the fastest-growing part of IT spending, according to market researcher International Data Corp. The information security industry is also complex, especially for those who are less than tech savvy. Do you need a software firewall? A hardware firewall? Both? The fact is, while there are scores and scores of so-called solutions, none of them can solve every potential security problem facing today's Web-driven businesses. But there are some great systems; here are six that we like the best.

Best for... Cleaning up your e-mail system

Trend Micro Client Server Messaging Security for SMB

What it does: Viruses, spam, and phishing are the three-headed monster of e-mail. Trend Micro helps tame the beast. The company constantly monitors e-mail threats, sending software updates to fend off viruses, quarantine spam, and foil phishers.

What's cool: Trend Micro's system installs updates automatically and will do so as often as you like--even as frequently as once an hour--on all PCs and servers on a network, including those in remote locations. It notifies you if there's an unusual amount of spam coming in or efforts to phish for employee data. Trend Micro also removes viruses should your system become infected.

Drawbacks: The SMB client server runs on Microsoft's Exchange server, so non-Exchange users need a different product. It also does not block spyware or unwanted content (though Trend Micro has other products that do both).

Price: $241 a year (for five users) to $44,100 a year (for 1,000 users)

Best for... Wireless users

Meru Networks MC500 and AP200

What it does: These days, more computer users are being linked via in-house wireless networks. Meru, which makes components for corporate wireless networks, offers supercharged security protocols and data encryption to ensure that hackers can't sit in your parking lot and read your e-mail.

What's cool: Most wireless networking equipment will detect an attempt by an unauthorized or unknown user to get access to your network. Meru's security equipment goes even further, jamming and scrambling those rogue signals.

Drawbacks: Meru can secure your company's wireless network, but you can't take it with you on the road. In other words, e-mail sent from public wireless networks (say, from home or the local Starbucks) is not protected.

Price: Starts at $2,300, for a network of about 10 people

Best for... Backing it all up

What it does: Say a virus gets inside your network and corrupts your data. SonicWall's CDP (for continuous data protection) is a giant hard drive that constantly saves the data on your network, allowing you to restore a clean version of all the data on every networked PC at the click of a button.

What's cool: SonicWall uses hard drives rather than the tape used by many other data backup providers. Simply connect SonicWall's CDP to your network and it captures data and gives it a time stamp every time someone saves. That's true for workers on the road too, as long as they're connected to the network. SonicWall's hard drive also sends an encrypted copy of its data to a bombproof location in case of emergency.

Drawbacks: The backup system works only with data that's on a company network. So if a notebook is stolen, you can recapture its data from its last save--but you can't keep the data off the streets.

Price: $1,999 (for a 192-gigabyte hard drive) to $7,999 (for a rack-mounted 1.2-terabyte drive)

Best for... Handing off the problem to someone else

Nexum FirstDefense for SMBs

What it does: If you can't afford an in-house security specialist, outsource the task to Nexum, which will set up a comprehensive security system and run and monitor it, 24 hours a day.

What's cool: Nexum consultants and engineers will inspect your network and systems for security weak points and then fix them. The company handles every element of security, from vulnerability scanning to putting a lid on spam. It also makes sure that all of your security products are up to date.

Drawbacks: Outsourcing means giving up control as well as headaches. Another issue is that outsourcers work only with certain products; Nexum, for example, does not work with SonicWall firewalls. So if you have a security infrastructure in place, you may need to purchase new equipment.

Price: $200 to $1,500 a month, depending on the size and complexity of the client

Best for... An all-in-one solution

Fortinet FortiGate-60M

What it does: FortiGate combines hardware and software in a single box to provide a one-stop shop for basic business security. It includes a firewall, antivirus software, tools to detect if people are trying to invade your network, tools to stop them, content filtering, and features to boost network performance.

What's cool: Despite all the features, FortiGate is simple to manage. And as your company's needs change, there's an entire family of products to help you, for example, add wireless capabilities or more users.

Drawbacks: Convenience has its price. In other words, all-in-one products generally are good at everything but great at nothing.

Price: $895

Best for... Managing software updates

Shavlik HFNetChkPro

What it does: Software changes fast, and no one has time to track all the updates and security patches that vendors seem to be releasing on a daily basis. Shavlik's software tracks patches offered by leading software vendors--including Microsoft, Apache, and the Firefox browser--and makes sure you know about them.

What's cool: When software patches and updates are released, Shavlik's HFNetChkPro automatically installs them on every computer on a company's network. In most cases, users won't even know their computers are being updated, though Shavlik's software issues a message if a patch is significant enough to require a reboot.

Drawbacks: Shavlik systems can be difficult to deploy across multiple locations; to do so, you may need to purchase separate licenses for the product.

Price: From $93 for five users to $14,685 for 999 users, plus an annual maintenance fee of 25 percent of the cost