I usually suggest somebody just starting out to look at Knoppix << www.knoppix.net
>>. It boots and runs right from the CD. That means it will seem a bit slow, but it gives a really good idea of what Linux is.
After that, you can research different distros. A good place to look is DistroWatch << www.distrowatch.com
>>. Most newbies start out with an "easier" version such as Fedora (which used to be RedHat), Mandrake, or SuSE. If you are more computer-inclined, you could try Debian or Slackware. They might be a bit tougher for a newbie to install and configure.
Once you have a handle on those, you can look at Gentoo << www.gentoo.org
>>. Installing Gentoo is an education in what Linux needs to run.
Then, you can look at Linux From Scratch << www.linuxfromscratch.org
>>, where you build and install everything manually. I've always thought it a bit of a misnomer, though... You need a running Linux system to create a LFS system.