Where can you get security for Linux?
Security is a concept, not an application. You get security in Linux by making the system secure.
Currently, Linux is less secure than Windows in most regards, due to the SSL certificate authority Linux uses selling secure information to other organizations. However, Linux is still more secure than Windows in that the security problems Linux has are less serious than the security problems Windows has. Windows is more exploitable than Linux.
There is security on Linux and there is no security on Windows. Well, there is, but it's quite weak compared to Linux. Among other: -Better rights management -Kernel security modules, some of which were developed by US government, and some by security-specialized companies, so you have the idea. -Since Linux is extensively used for server solutions, you can guess that most of server software is pretty much top-notch.
No system is secure forever. Therefore, yes. To make it secure you should update / upgrade to stay secure. It provides security updates just like Windows. The good thing with linux is that it is hard to find a virus written for linux. Even if there are, most of them won't work because linux doesn't auto run.