ClamWin

Yes, you can infect your personal files by plugging in your portable drive into another computer.

Do not trust a strange computer. Run an antivirus program. These days, it is not an option. It's a necessity.

LastPass

The Last Password You'll Have to Remember

Single Password
If you're like most people, you use the same two or three (or one) password for all your webite logins. Not good. LastPass is a service that lets you use an unlimited number of paswords and logins for different sites, but only have to remember one. Your passwords are transmitted and stored encrypted on their servers, allowing you to access them from anywhere.

KeePass

Perhaps you don't want to save all your files, but only want a handy place to keep all your passwords. I used to recommend PINs for this category, but KeePass is open source, a big plus for encryption software.

TrueCrypt

TrueCrypt isn't just listed because it's portable software. It's listed because it's the best, portable or not. You can create a virtual drive of any size you choose that contains all your private data and information. You can use it to encrypt your entire USB drive or only a segment of it if you prefer. I highly recommend this tool.

KeePass

I know what you do. All those different passwords you need to register for those websites? You use the same one, don't you? Your mom's middle name, right?

It's really hard to keep track of all the passwords and PIN numbers we need today. A password manager saves them all with a master password, so you only have to remember one. Then you can use a different one when registering at that cat-fanciers website.

Eraser

Most people know (or should know) that if you delete a file, it's often recoverable with the proper tools. Even if you've written data over the exact spot on your drive where the file formerly existed, there's a good chance that an expert can recover it. Additionally, Windows squirrels temp files all over the place, and there's a good chance that multiple records exist in more than one place. Thus the need for secure file deletion.

TrueCrypt

Outstanding product. Create virtual drives of any size with several different encryption techniques. One very interesting feature is the ability to create a "plausible deniability" drive, so that if you're tortured to reveal the password, you can have a spoof drive with fake data. In case you're worried about being tortured.

http://www.truecrypt.org/

AxCrypt

Very simple to use. Right-click on any file and select "encrypt". To open, double-click and enter password. What could be easier?

http://www.axantum.com/AxCrypt/

ZoneAlarm

Everyone knows what a virus is and that you should protect against it, but what is a firewall? A firewall does two things: 1. It blocks intruders trying to access your computer from the internet or a network. 2. It blocks unauthorized programs on your computer from accessing the internet. Okay, you see why the first thing would happen, but why the second?

If you are truly paranoid about leaving tracks on a visited computer, run Restoration to see what files may be undeleted after you leave.

Microsoft Antispyware Beta

Ad-Aware SE

Spybot-S&D