It’s important to remember that all computers (even Macs) can be harmed by malware. But, armed with common sense, you can easily protect your computer from trojans and viruses.

Apple recently updated this article about protecting your computer (and your data) from malicious applications: Safety tips for handling email attachments and content downloaded from the Internet

Smith College ITS also recommends McAfee Virus Scan for Mac OS X, which is a free download from the Smith Software page.