One of the most frequent responses I get when trying to introduce Linux to friends and acquaintances is: 'Yeah, I should learn Linux'. I try to clear up the confusion by telling them that there really is not much to learn at this point in Linux's development cycle; pretty much anyone who can hit a power button, operate a keyboard and mouse, and burn a CD can learn Linux. That is to say that there is little to no learning involved, provided you choose your distro well. If a completely boneheaded Mac fanboy like myself can get going in a matter of days, then anyone can. They often refuse to listen, saying something like: 'But the Command Line!'.
And yes, it took me a few days, not hours or minutes to get going because my first distro of choice was OpenSuse; if I had chosen, for example, Ubuntu, or LinuxMint, then it would have been hours.
As it is, I'm well into a cycle of 'Distro Derangement Syndrome', (h/t rachelmap!) or DDS. Webster's, I believe, refers to it as 'A gradual loss of thoughts of anything not related to Linux, due to the dizzying embarrassment of choices available', though I could just be pulling that out of thin air.
In fact, I've got a particularly severe strain of DDS, as I'm using SabayonLinux, which comes loaded with eight window managers, every choice app under the sun, Compiz/Beryl, Metisse, and a whole lot more. When I log into my Intel iMac (not often these days), it's like traveling back to the Stone Age in terms of technology.
Now there may be valid arguments as to whether Ubuntu and the like are truly open source, as they use a number of proprietary (and closed source) codecs and drivers, and if you were to ask Richard Stallman or the folks at the GNU Project, or the Free Software Foundation (home page here) then you would likely receive a resounding 'No' in response.
I want a computing experience that 'just works'. And for me, with my limited budget and skill sets, Linux 'just works'. No DRM (oops, wrong link), no EULAs (more here, and here), no TPM, and no crippleware.
If I was true to my ideals, I would only listen to music in the Ogg Vorbis standard, and my video in the Theora standard, so that's a difficult conundrum to solve. I'm hopeful that as more folks switch to Linux, the pressure on big corporations to open source their drivers and codecs will become irresistible, and then we can all live happily under the GPLv3.
Ahem. Back to the topic at hand. If you want to get your hands messy and compile things the old skool way, then install Gentoo or Slackware; if you want a user-friendly GUI, then there are an abundant number of choices, here, here, here, here, here, and here; if you want to mix it up un petit peu, then you can't go wrong here, here, here, here, here (!), and here. More on lightweight editions can be found here, and the absolute basics can be found here.
A couple of caveats, if this is your first Linux install: one, unless absolutely necessary, try to have an ethernet connection during install, it'll save a bit of time; two, once you have the system installed (or have the liveCD going), poke around and make sure that it correctly senses all your hardware, wireless card, network, etc.; three, keep in mind that the liveCD (or DVD) will be slower than the installed version, but if it's slow to the point of being unusable, then opt for a lighter version.
Just a few short months ago, it was well nigh impossible to get an encrypted network connection with network-manager (GNOME), or knetwork-manager (KDE) or, if you could get an encrypted signal, it was with the insecure (some would say laughably insecure) WEP protocol.; that has all changed now, with many distros including WPA and WPA2 in the various networking interfaces. In some of the mid-level distros, you may still need to install the package that allows you to have WPA/WPA2, but if you're using one, you probably already know that.
Below is a clip of XGL running on Fedora Core 5: