Level 5Linux and Mac OS X. They both implement high-level security that can not be accessed without explicit permission (read: password protected on base level).
Linux is known as a winner in the security contest as far as viruses/worms/malware goes. However, it isn't for everyone, for one reason or another. I love it, but only as a second OS, dual-boot with windows for instance. There are a lot of free apps and basically if you just starting up with computers, I'd strongly recommend linux ubuntu. It can be installed on (almost) any computer, runs smoothly, has beautiful graphic interface, it is secure and it has an alternative for the best windows apps.
Mac OS X is also a great and secure OS, due to it's relatively low number of users and therefore relatively low number of viruses and other threats, comparing it to windows. But, it is hardware dependent. In order to get the best out of it, you need to use it with apple hardware.
Level 4The best security is to be cautious as a user. Yes, the UNIX based OS's are considered generally more secured, but you should be perfectly fine using up-to-date windows with free avg installed. That said, If you start clicking on every "You just won an iPad2" banner, be warned that no linux will be able to protect you.
http://downloadlinuxfree.com/
the first is a test to help you chose one, the second is a site with many links to different distros.
Linux is known as a winner in the security contest as far as viruses/worms/malware goes. However, it isn't for everyone, for one reason or another. I love it, but only as a second OS, dual-boot with windows for instance. There are a lot of free apps and basically if you just starting up with computers, I'd strongly recommend linux ubuntu. It can be installed on (almost) any computer, runs smoothly, has beautiful graphic interface, it is secure and it has an alternative for the best windows apps.
Mac OS X is also a great and secure OS, due to it's relatively low number of users and therefore relatively low number of viruses and other threats, comparing it to windows. But, it is hardware dependent. In order to get the best out of it, you need to use it with apple hardware.
Here's a topic about linux and the security, we've discussed earlier: http://www.meetgadget.com/gadget/15072/Linux+Ubuntu/discussions/843/Is+Linux+Safe-