There are plenty of Distibutions to choose from that will do what most users do in their dayto day lifes with a computer. The thing is to find the one that works for you.
Personal choice is the thing I like the most about FOSS (free open source software). The criteria I use for choosing a Distubtion are simple:
1: Stability. I want a good code base that is well tested and proven. I don't mind software that is still testing but the core system has to be stable.
2: Security. This is rarely an issue with Linux because it is designed to be secure from the ground up.
3: Available software. By this I mean large repositories and back ports for those non-free packages that make an OS usable for more than just the basics.
Though there are a number of independent distributions most are forked from five main ones.
Slackware is the oldest and is so because it is rock solid. This is one of my favorites.
Debian is one of the most developed distros and the base for a large number of very good distro. I've preferred Debian based distros for years now.
Red Hat/Fedora is a good place to start for most people. It's been devloped for ease of use and has a long commercial history that caters to enterprise solutions. You don't stay in business making bad software.
SUSE(Novell) is another enterprise oriented product that is also excellent. I currently have OpenSuse 10.3 loaded on a machine and am finding that the long avoidance I've had for since I tried it several years ago was not justified. It has become a very nice disto and is worthy of anyones consideration.
Mandriva is another fine distro and has released it's latest version recently. I haven't had much to do with it since it was Mandrake other than PCLinuxOS. The reviews are good and with a long history of development it is a proven performer.
As for what is right for you that is going to be up to you to decide. Try as many Live CD's as you can download until you find the one you want to install and give it all the effort you would give to learning Windows. Linux is not Windows but they both have about the same learning curve in my experience and to me Linux makes more since in the way it handles everything from system resources to security to multi-user environments. I have found that once I got use to the freedom that Linux offers I had been missing the real fun that there is in the world of computers.
And if you have enough hard drive space you can always install more than one on the same machine like I do then play and learn to your hearts content.
Currently installed on my main machines
Debian 4.0 (KDE)
Window XP HE sp2
Windows Vista business edition
SimplyMepis 7.0 beta 5
I have various other machines I use to test other Linux distros and open source solutions to other things of interest like networking and thin client.http://linuxtracker.org/http://distrowatch.com/http://www.madtux.org/