what is more likely to give a macbook pro a virus facebook or email?

[macdudeosx]

Neither, unless you manually downloaded an application and it has asked for the root password, there is no virus. Macs do not download and automatically run applications - they cannot do it.

Unlike Windows, Mac OS X applications don't share a common registry. Mac OS X applications use individual preference files, thus the types of global configuration changes which enable so much of Windows malware is simply not feasible on a Mac. Further, on Mac OS X, the Web browser is not integrated into the operating system - it's a completely separate/independent application. This isolates the browser - a common infection point for Windows users - and helps insulate the Mac OS from external attack. Root access is needed in order for malware to interact with other programs (i.e. steal passwords, intercept transmissions, etc.) By default, root access on a Mac is not enabled. Mac's also do not auto run applications like Windows does, eliminating apps that download and run behind your back.