Do you use a Pen-Drive for transferring data across different systems in your office/network, then there is a high possibility of virus infections for transferring across with the pen-drive as a medium.Here are collection of freeware tools that you could as your first line of defense before using your pen drive on other systems.
1.USB Write Protector –This freeware application prevents write access to a USB drives. This will protect USB drives from viruses, malwares, spywares etc.Using this tool you can just copy data from your pendrive to the system but not copy data into the pen drive from the client system.Its only 190 KB and works with XP with SP2.
2.Portable Antivirus Solutions —
ClamWim Portable — ClamWin Portable is the portable version of the open source Free Antivirus program.
- Update the virus signature from the regularly updated Virus Database directly from the USB.
- It also detects spyware.
- It takes about 25 MB after installation on to the USB drive.Homepage || Download
Dr. Web CureIt — In case the file you want to copy into your USB pendrive is infected with a virus, 
3.USB Firewall — USB Firewall automatically detects malicious autorun.inf file when an infected USB device is infected, you can also see what command are written in the autorun.inf file which launched the program and decide whether to let it run or delete the file and the file autorun.inf which launched it.
