Most of the time, one operating system per computer is enough. But on occasion, you might want to boot up a second operating system for security reasons, testing purposes, or compatibility with specific software. Technical details typically restrict that alternate OS to a single PC, however. You can only install an OS in a single location after all.
But using a fork of Oracle's popular VirtualBox virtualization software, known as Portable VirtualBox, you don't have to limit secondary operating systems to a single computer or boot it up separately from Windows. Instead, you can pack it onto a portable USB drive and load it up on any PC while Windows runs in the background, like a virtualized version of the Windows to Go option found in Windows 8 Enterprise.
Portable VirtualBox is fairly easy to set up, though it does require attention to a few key details. We'll walk you through it, and outline some of the main concerns with running a virtual machine on a portable USB drive.
Things to consider
The one major caveat with Portable VirtualBox is that it requires administrator privileges to run. That shouldn't be a problem if you're setting this up at home, but it's not the most practical solution for enterprise users, because the IT manager would need to be around to plug in a password.
VirtualBox also consumes a certain amount of hard drive space and memory--both of which you can adjust when setting it up--as well as processing power. That means you'll need a big-enough USB drive to contain whatever operating system you install--1.5GB for Windows XP and 5GB for Ubuntu, to name a couple of examples--and you might have problems using a virtual machine on a five year-old netbook with limited resources.
Also, keep in mind that VirtualBox doesn't come with any actual operating systems. You'll still need to supply your own installation files, and in the case of Windows, your own serial key to validate your copy of the software. (If you're looking for something free to mess around with in VirtualBox, Ubuntu should do the trick.)
Finally, consider reformatting your USB drive as an NTFS file system, because the FAT32 system used by some USB drives will limit file sizes to 4GB. To reformat a drive, right-click it in Windows Explorer, select Format and choose NTFS under the File System menu. This will delete all the drive's contents, so make doubly sure you're formatting on the USB drive you intend to use, and not any other drive on your system.
Setting up Portable VirtualBox
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