Carry a PC in Your Pocket With a USB keychain drive and a little forethought, you can carry a personalized computer everywhere and leave your laptop at home.

A notebook PC is a handy thing to have, but lugging one around everywhere you go can be downright inconvenient. Fortunately, there's a solution that fits right in your pocket: The ubiquitous USB flash drive, often called a keychain or thumb drive.

With the right device and software, you can plug your flash drive into a computer at an Internet cafe, hotel business center, or elsewhere, and have all the tools and files you need to do your work--complete with your own personal launch menu. Sure, you can use online applications like Google Docs or Zoho Office (see Life Without Desktop Software for more on these), but a flash drive lets you carry a much wider variety of the applications, utilities, and other fun doodads you've come to depend on.

Here's everything you need, from hardware to software and beyond, to get going in the world of pocket computing.

Harness the Right Hardware
To get the most out of portable computing, you need a good flash drive. Here are some things to consider:

Take a drive on the reading edge. The faster your flash drive, the more smoothly programs will run. When shopping for a drive, look at the specs and try to find one with a read rate of 15 mbps (megabits per second; in megabytes, 1.9 MBps) or faster. If you already have a flash drive, you can test its speed with a free utility like HDTach for Windows.

Look for high-speed USB. A USB 2.0 flash drive will perform much better than USB 1.x. Make sure the drive you buy specifies USB 2.0 or "high-speed USB."

U3 or not U3? Some flash drives (notably those from SanDisk) are labeled "U3," meaning they use a proprietary format to create applications for USB drives. Such drives usually come with a built-in pop-up program launcher called LaunchPad and a few programs, or they at least link to a Web page for downloading and installing free and for-pay U3 applications. SanDisk claims that only U3-compatible programs will run on such a drive, but I had no problem running U3 and non-U3 programs side by side on the same memory stick. (However, don't expect your non-U3 apps to show up on the U3 launch menu.)

With so many portable applications available from a variety of free sources these days, you don't necessarily have to get a U3-equipped drive. If you do have one, you can either take advantage of the LaunchPad feature and its various apps, or you can find utilities for removing U3 LaunchPad software from SanDisk drives and from non-SanDisk drives. And if you change your mind about such removal, SanDisk has a free tool for getting it back.

Snag the Best Software
Once you've got the flash drive of your choice, it's time to stock up with the tools you'll need when you're away from your regular system. The term "portable software" usually refers to an application that can run from a single folder (usually on a removable device) without adding any files or Registry entries to the host system. Although this leaves out the traditional behemoths like Microsoft Office or Adobe's Creative Suite, you can still find a lot of handy software that meets the portable requirement.

Your suite is waiting. If you want an all-in-one package of basics--spreadsheet, word processor, graphics--you can have your pick of portable suites, all completely free (in some cases, donations are accepted).

An excellent collection is Portable Apps, which comes in two sizes, Standard (260MB installed) and Lite (105MB installed). Both versions include an antivirus program, a Web browser (Mozilla Firefox), an instant messenger (Gaim), a Sudoku game, a calendar and task manager (Mozilla Sunbird), and an e-mail client (Mozilla Thunderbird). The Standard version also comes with a portable version of the OpenOffice suite, while the Lite version has the AbiWord word processor instead.

Another all-in-one free collection can be found in winPenPack. The winPenPack suites come in more flavors than Portable Apps--Essential, 1Gb, School, Game, Web--and there is even an option to make your own. You can also download individual applications. The offerings fall into a wide range of categories--from office, Internet, graphics, multimedia, and development to security, system, and utilities. The choices include considerable overlap with PortableApps, with both offering Mozilla and OpenOffice products, for example.

What's for launch? Running your portable applications will be easier if you have a pop-up menu launcher. You'll find one in U3 flash drives, as well as in both PortableApps and winPenPack. In each case, an icon is added to the taskbar tray (the icon-studded area near the clock); click it to see a Start-menu equivalent that lists the applications on your flash drive. Personally, I find the winPenPack launcher to be the most flexible and easiest to customize. You can download this launcher separately from winPenPack. If none of those meet your needs, you can try still another free portable app launcher, PStart, from Pegtop Software.

Roam the lands of the free. But big collections are not the only place to find portable applications. Sometimes you can find a portable version of your favorite program just by using your favorite search engine, entering the application name and then "portable" as keywords.

Other good places include sites like Portable Freeware and the portable freeware section of Ned Wolf's Absolutely Free Software site. Another site where you can find a portable section is Snapfiles.

Finally, try entering the keyword "portable" in the search box of your favorite software download page--for example, at (where else?) PC World Downloads.

Do Right by Your Data
Whether you carry your work files with you on your flash drive or store them online, you'll still need to take some precautions to protect those files, your privacy, and your computers from harm, whether accidental or malicious. Here are some steps to consider.

Scan for safety. Since using your USB drive on an unknown computer exposes the drive to additional risks, be sure to install antispyware and antivirus software as part of your set of portable applications. As an additional precaution, scan the flash drive itself from your regular computer the next time you return home to make sure it didn't pick up any bugs.

Use common sense. Because a host computer like one in a hotel business center or an Internet cafe may have keyloggers that record your passwords, portable computing can never be 100 percent safe. But you can limit the risk by avoiding credit-card transactions when using your portable system on another machine. And it goes without saying that you should avoid online banking in these situations.

Shred it; don't sweat it. If you're working on sensitive documents, you should keep them encrypted while stored on your flash drive. For example, the open-source program TrueCrypt or the freeware archiving program IZarc2Go both offer encryption features that run on a flash drive.

In most cases, you'll have to copy documents out of the encrypted folder or container before working on them, and then copy them back when you're done. For added security, use a shredding application to destroy the work copies (after you've put a copy back in the encrypted folder of course). CyberShredder and UltraShredder are two free portable utilities that do the job.

Back up your portable, too. Because these devices are small and easily misplaced, backing up your portable USB "computer" is arguably even more important than the backups you do for your main system. The applications are much smaller, so backing up is faster, and the resulting files take less room on your backup drive. All of the suites mentioned above include backup utilities.

Of course, you don't really need such a utility; you can always just use Explorer to drag and drop the contents of your flash drive to a backup disk. The important thing is to do it regularly.