Currently Being ModeratedNov 29, 2012 5:31 PM (in response to vickie0718)
Yes. Use ClamXav.
Currently Being ModeratedNov 29, 2012 7:02 PM (in response to vickie0718)
Are the other infected machines at your school Windows computers? If so, whatever virus is infecting them cannot infect your Mac. There are no viruses that can infect a Mac by simply using a USB drive with the virus on it. All Mac malware at this point requires you to explicitly open something, and even then, they are quite rare. You should be fine.
Of course, if you want to scan that drive to avoid passing on any Windows viruses, you've got a few choices. ClamXav is okay, but some recent testing I did shows that it doesn't do a great job of detecting Mac malware. (See Mac anti-virus detection rates.) Of course, this doesn't say anything about detection of Windows malware, which I didn't test... but still, it may be a better idea to download something like Dr. Web Light from the App Store for a simple and quick scan of that drive. (Assuming you're using a version of Mac OS X that has the App Store.)