This is an antivirus program that you can use anywhere. It can scan a hard drive, a folder or an individual file. Run it directly from your flash drive, iPod, portable hard drive or a CD. It can be used on any computer.

The only catch is that it does not download updates automatically. Make sure to check for updates whenever you use an Internet-connected computer.

ClamWin Portable takes up 13 MB on a thumb drive. It works with most versions of Windows, including Vista.

Cost: Free

Link: portableapps.com