I would like it to be secure and stable.

linux comes in many flavors called "distributions" or "distros". since it's free and easy to program (if your a programmer), many people have come up with thier own versions. there are versions made for security, multimedia, etc and include customizations for people that like those things. The distros can be downloaded from sites called "mirrors" that are located in all countries of the world, just find one near you.

This site, rates distros by popularity and provides links for many:

http://distrowatch.com/

links to distros:

http://www.linux.org/dist/

http://distro.ibiblio.org/pub/linux/dist...

a linux cd is packaged in a file called an ISO. to use the ISO, burn it with BurnCDCC from http://www.terabyteunlimited.com/utiliti... using that program makes sure that the cd is created correctly.