Here is the thing you need to do when you are experimenting with linux.

Make a list of your goals.
At first, usually everyone's goal is 'try something new', or 'see what it's about'.
The best distribution of linux to get a feel for what it is for falls under the LiveCD categories. Currently the top three LiveCDs for this is SLAX linux, Kanotix, and Knoppix, in that order.

If you want to install on your computer and dual boot to see if you can switch everything to linux (except gaming) then you want to try madriva (used to be mandrake), fedora (los red hat!), or a hard drive install of SLAX, or possible beatrix.

If you actually want to learn why linux works the way it does, or why it is gaining popularity, and get into the reasoning etc, use Arch Linux. Period.

A little about Arch Linux. Arch linux is the simplist, most fool proof way to learn about linux, how its set up etc, without losing yourself or screwing anything up. All the defaults are wonderful, and the installation tells you exactly what is going on and why. It installs a base system on your computer, that is just enough to log on, do some config editing if you want to, and get internet access. Then arch starts to shine. Pacman -S "gaim" and it will download and install the latest version of gaim on your computer, optimized for i686 (P4 / AthlonXP or later) processors. Unlike gentoo, no compiling is necessary, and I ran benchmarks myself of gentoo vs Arch and there were only very specific cases where gentoo beat arch (basically 10% of the tasks I normally do on linux were faster on gentoo). This is with me changing the use flags, the optimization flags and everything on gentoo.

A little about me to know if my goals / opinions are similar to yours:

Distributions I've Tried:
Gentoo Linux (2004 series and the last edition of 2003)
Sorcerer Linux (pre 2004)
Lunar Linux (2004)
EvilEntity (2003)
Knoppix (still use for specific tasks)
Kanotix (use regularly)
SLAX (regular and KillBill editions)
PHLAK (excellent for its purpose, the hard drive install worked well too)
Ubuntu (this was a mess...I will explain in a bit why I didn't like it)
Red Hat (pre 7)
Mandrake (2 quarters ago, and only for a day)
Debian (same as mandrake)
Arch Linux (current system)

A bit about Ubuntu:
Plus: Marketing. One Man Team. Excellent and Clear Goals and Focus.
Minus: It's far from linux. Basically this is a distribution to get if you just want to say 'i use linux' for the sake of saying it. The dependencies are not debian friendly, it is very easy to break the system if you change even the simplist settings (like which repository to download from even if the site says it is compatible). If you want to have an optimized, easy to use linux to jump in and try out everything linux has to offer Mandriva, and Debian distributions do it better than Ubuntu.

However, with that being said try Ubuntu. Try every version of linux you can because you will eventually find one that sticks with you, and thats the beauty of the OS - there is a version for everyone, that seems to be perfect for you.

What I Use Linux For:
- online chat, web browsing, music and movie watching, listening and converting
- programming, server setup (http, ftp, smtp, steam, unreal, other game servers)
- working (spreadsheets and word processing)

This is a rough reaction by me. I am sure I missed out on some things, if you want any help installing, configuring, maintaining, or just learning about linux ask away in this thread, through PM, IM, or email and I will be glad to help.

Just Some General Tips:
- Always have a backup system, install linux on a spare drive, make sure you have a way back, or at least a knoppix cd.
- Find out all the hardware models of your computer, video card revision number (not just Asus 9800 Pro 128Mb, which revision).
Network card make and manufacturer is a must. This will save you a huge headache if anything ever goes wrong. You want at least the info for your motherboard, network card, sound card and video card.

Thats all I can think of right now. Remember above all have fun.