David: How can a firewall help protect my home network? Is it better to use a hardware firewall or one that runs on your PC?

Jim and Neil: Firewalls can be a huge help. There are two basic types of firewalls: a hardware firewall, which is a dedicated firewall device in the network itself, and a personal firewall, which is a software firewall running on each computer.

Hardware, or network, firewalls protect the entire network from major intrusions, kind of like the lock on your front door. They are essential, especially if you have an "always on" Internet connection such as high-speed broadband Internet access. The good news is, many wireless routers are now offered with built-in firewalls and it takes just a mouse click to turn them on. When you purchase your wireless router, look to see that it includes a "Stateful Packet Inspection" (SPI) firewall built-in.

Personal, or software, firewalls protect each computer from several threats, including unauthorized sending of information to the Internet, "hidden" software installations from unscrupulous Web sites, and general actions on your computer that could be performed without your consent. Personal firewalls are also essential if you take your laptop to a hotspot or another location outside your home network. The good news is, there are very good personal firewalls available for free, such as ZoneAlarm, or even simpler, with Windows XP, as of Service Pack 2, a personal firewall is built into the operating system. It takes just a mouse click to turn it on.

At a minimum, you should install one type of firewall. Ideally, we recommend both. By the way, firewalls do little (if anything) to keep intruders from accessing your wireless network (see the previous question).

David: What's spyware and how can we protect ourselves?

Jim and Neil: Spyware, and a related category called adware, refers to stowaway programs, which are typically attached to "free" downloads (games, pictures, music, etc.), or sent to you via a Web site (which your system could be allowing depending on the security settings in your browser). Clicking on pop-up ads is another great source of these, so please stop clicking on the monkey to win money.

In general, there's no real danger to your system, or to your data from spyware, but these programs do "spy" on you, reporting back to the program owners (usually marketing companies) on the sites you visit and the nature of your on-line activity. That's enough for most people to not want it, but what's really obnoxious is that they slow down your computer and clog up your Internet connection as they report on you.

There are several good companies out there that sell anti-spyware software. Many offer a free trial period. If you've never checked your system for these programs, there's a good chance you'll be shocked by the number of spyware programs running on your system.

David: What is this "phishing" stuff I keep hearing about?

Jim and Neil: If it sounds too good to be true, it is. Doubly so for the Internet. Unfortunately due to the anonymity and extremely low cost the Internet can provide, it's an incredible medium for scam artists to operate. "Phishing" refers to sending you email that impersonates a company or organization with the ultimate goal to steal your information.