A couple of people have written and asked me to mention Portable Apps. PortableApps.com is the most well-known source for portable software, but there are many more programs that will run on a USB thumb drive. Many programs will even run from a thumb drive with little or no modification, for example, Skype on linux (and possibly on Windows too).
Portable Apps as offered by PortableApps.com are Windows programs that you can put on a USB thumb drive (or on any kind of storage device) that will run without needing to install them on the computer. The advantages to this are:
Firefox version 2 was recently released. I haven't had a chance to install it yet, but it is worth checking out.
Firefox is more secure than Internet Explorer, and has more features. Internet Explorer 7 has also been released, but based on the very bad security record of IE, it is not recommended.
Many people have expressed interest about portable apps for Linux. There are also a good selection of portable apps available for Mac OS X. You can probably find others in this excellent list from Wikipedia.
Portable apps will not really provide security against an infected public computer. They may actually reduce your security on public computers for the following reasons:
If you make web sites, you may be interested in the new portable web servers that are available. You can run Apache, PHP, MySQL and other tools from a USB thumb drive.
There is another portable webserver called WOS Portable that includes Apache, PHP (4 and 5), MySQL, ImageMagick, and the Typo3 content management system. The "WOS" is for "webserver on a stick".
This section of LinuxForTravelers.com shows you how to create and use an Ubuntu Linux live CD. This tutorial is written for Windows, although the basic process is similar for Mac and you will probably be able to follow along. All screenshots are from the latest Ubuntu 6.06 release.
Ubuntu Linux is generally used as a regular desktop operating system, but the live CD so good that I'll use it as an example of how to make a live CD.
With the Ubuntu live CD you can surf the web securely with Firefox, edit office documents (including Microsoft Word, Excel and Powerpoint files) with OpenOffice, edit digital photos with the GIMP, make Internet phone calls with Ekiga (compatible with SIP, H.323, Microsoft NetMeeting, etc.), and much more. Unlike with Windows, viruses are not a serious problem with Linux, and since the operating system runs from a CD-R, you will have a fresh operating system on every boot.
Ubuntu Linux is free. The download is almost 700MB so you should have a high-speed Internet connection, or you should go to an Internet cafe that has a high-speed connection. If you don't have access to a high-speed Internet connection, you can order Ubuntu CDs online here and get them shipped to you by postal mail for free.
Internet Explorer is not very secure and if you use it you may end up with a lot of unwanted spyware. Firefox is a free alternative browser that prevents a lot of problems caused by Internet Explorer.
Why Internet Explorer is Unsafe
Internet Explorer is unsafe partly becuase it uses a feature called ActiveX that can allow software to install on your computer without your permission. A current list of Internet Explorer security flaws can be found on Secunia's Vunerability Report. More information about why Internet Explorer is unsafe can be found on BrowseHappy.com.