Even if you have a computer at home, on occasion you'll find you need to use the public computers at a library, internet café, or your local copy shop. Traveling, technical glitches at home, or the sheer convenience of checking on something right now brings almost everyone to a public computer once in a while. It brings a few people -- whether they own computers or not -- to public computers daily.

I have a confession to make. In a former life, I was a systems librarian. I know what's on public computers. No, I don't have your personal information. I removed that from the public computers, along with a lot of keylogging software, viruses, and spyware. What I do have is a few little tricks to keep your private information private.

The cardinal rule of public computing is the most obvious. It's also the one most often broken. Sometimes there's no avoiding breaking it. Sometimes, though, it seems there is a digital variety of the "belief in immortality" that's usually attributed to young adults. This digital immortality seems to affect people of all ages.

The cardinal rule? Don't put private information on a public computer. This means, despite the fact that the IRS encourages electronic filing, don't file your taxes online at the library. If you have no other access to a computer, file the old fashioned way. Trust me on this. It maybe faster and easier to do online, but not if your entire family's social security numbers are picked up by a keylogger.

The cardinal rule also covers more mundane things, though. When you access sites with a "Remember Me" option, make sure it's unchecked. Be sure to physically log out when you're done. It seems really paranoid and obvious, and people still don't do it. If I had a dollar for every library patron that opened up Yahoo! mail and asked me why they were getting l0v3rboi6969's messages.

So what if you do have to break the first commandment of public computing? What if your old computer is in a smoldering heap on your desk at home, and you have no choice but to order one from an online retailer? There are a few things you can do.

Ask your friendly library professional, or internet café attendant, whether the desktop session resets on log out. If it doesn't, you have two options. You can either ask permission to clear the cookies, cache and temp files yourself, or you can ask your friendly library professional or internet café attendant to do it for you (if the computers are locked down, they'll have to). If the desktop session does reset, ask if it clears cookies, cache, and temp files, or any combination thereof. I've seen some software designed to erase sessions that really doesn't work as desired.

Another alternative is to BYOB (bring your own browser). Portable applications are great. You can install web browsers, mail clients, and office suites on flash drives, and bring them with you. Since you're not installing anything on the host computer, and because many portable apps keep your associated information on your flash drive, they're an excellent way to keep your data safe and the systems librarian happy.

Be aware, as well, that there are often prying eyes at public computer terminals. Usually if someone's giving you the hairy eyeball while you're at the computer, they're either putting a whammy on you so that you'll finish your session faster and they'll get a turn, or they're trying to see what you're doing. I've found it's more often the former than the latter, but if you are entering sensitive information and someone's looking you over a little too closely, minimize the browser and (politely) ask them to give a little space.

Always remember to exit your browser before you end your computer session. If you are at a computer that has timer software, and you leave your session before your time is up, log out. It's a nice sentiment to leave your session running so someone else gets a little more time, but it opens you up to the very real risk of someone seeing your information that shouldn't.

There are, of course, other risks inherent with public computers. I'm talking about viruses. Even if the computer is equipped with anti-virus software, can you really be sure the software is up to date? Don't count on it. Viruses don't follow a set schedule, and, unfortunately, public computer maintenance often has to. So that file you downloaded to your flash drive may not have sounded any alarms with the computer's anti-virus, but that doesn't mean it's safe.

Watch out, especially, for macro viruses in Office programs. Generally, it's a good idea to avoid using macros on public computers (and indeed, many places have disabled them for this reason).

It's not far-fetched to suggest scanning everything downloaded or created on a public terminal before you put it on your own machine. It may even be beneficial to scan with a couple different virus scanners (the one on your machine, and a free online scanner, such as Trend Micro's HouseCall).

Public computers are risky by nature, but you can minimize the risk. Even if you have to break cardinal rule number one.