There may be times when you're at a hot spot when you actually don't want to connect to the Internet. In that case, you can guarantee absolute safety -- disable your wireless adapter so you can't connect.
If you have a wireless PC card, you can simply remove it, of course. If you have a wireless adapter built in to your PC, you can disable it. In XP, right-click the wireless icon, and choose Disable. If you're using the adapter's software to manage your connection, check the documentation to find out how to disable it.
If you're using Windows Vista, choose ControlPanel-->Network and Sharing Center. Then in the Connection area, click "View status," and from the screen that appears, click Disable.
Watch out for shoulder surfers
Think all hacking is high-tech programming? Think again. "Shoulder surfers" don't need to know how to write a line of code to steal your password -- all they need to do is peer over your shoulder as you type. So make sure no one seems to be paying too close attention when they're directly behind you.
In addition, if nature calls because you've had too many double lattes, don't leave your laptop unattended when you go to the restroom. Laptop theft has become common in some places, most notably San Francisco, which was subject to a laptop crime wave. Consider bringing along a laptop lock and locking your laptop to a table. Some cafes even include ports to which you can lock your laptop.
Beware phony hot spots
Watch out for this latest hot spot scam -- someone surreptitiously sets up a hot spot near a cafe, created for the sole purpose of stealing personal information. You're asked to type in sensitive information in order to log in, and the thief makes off with your passwords and financial information. Ask a staffer at the cafe if there is, in fact, a hot spot available, and what its name is. Only connect to that network. And if you see two hot spots with the same name, don't connect to either --- one might be a so-called "evil twin" set up by a snooper to trick you into connecting to the phony hot spot.
Turn on your firewall
Windows XP and Windows Vista both have personal firewalls built in, so turn them on. In Windows XP, choose ControlPanel-->Security Center, then click the Windows Firewall icon at the bottom of the screen. From the page that appears, select On, and click OK.
In Windows Vista, choose ControlPanel-->Security-->Windows Firewall. The screen that appears will tell you if the firewall is turned on. If it's not, click Change Settings, select On, and click OK.
Windows XP's personal firewall is underprotected because it doesn't include outbound protection. (Windows Vista's firewall includes two-way protection.) If you're a Windows XP user, consider getting the free version of ZoneAlarm, which has both inbound and outbound protection.
Preston Gralla is a contributing editor for Computerworld.com, and the author of more than 35 books, including How the Internet Works.