Viruses are often spread by something inserted into the orifices of unprotected hosts, although some are virulent / evolved enough to get around basic protection as well. In Thailand, USB drives spread nasties faster than digital treatment can be applied, so after several years of taking care of many computers, I've decided that vaccination is the best option*.
This consists of planting a hidden and practically undeletable AUTORUN.INF file in the root of a removable drive.
I use Panda USB to vaccinate. Why? Because pandas are gay, and so are viruses.
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*Like all vacs, you run a chance of getting sick if you have a reaction. Specifically, you could lose all the data on your NTSF-formatted drive in a worst case scenario (most "handy" drives are formatted FAT32). My advice is not to use this feature until it comes out of beta.
