I like Ubuntu Linux and its secure and free, but if you like to play video games that are written specifically for Windows systems, you can get some of them to work through WINE.
Other than that Linux is very secure and has tons of free software available. I use a few versions, but Ubuntu is probably the most home user friendly and popular.
I like MINT, Fedora, and Ubuntu, as well as the LIVE Distro Knoppix which is a version that can run directly from a CD or DVD disc and without the need for a hard drive. Knoppix is mainly used by me for accessing NTFS file system when there is viral stuff on the drive, however I used it on some old systems at a prior workplace for non-infectable systems in break rooms for employees to be able to check their e-mail and the weather and news etc, and it couldnt be compromized to do evil on the corporate network. Mounted the CD Drive internal to the case, USB port and floppy drive disabled, and only the PS2 keyboard and mouse used for user interaction, so that no one could try to be smarter and insert any other bootable media into the CD drive.
