You know, Ubuntu is available in their own taste.
So there is Gobuntu if you want to make your own Linux Distro, EEE Ubuntu for Asus EEE PC's, Edubuntu for classrooms and Ubuntu Mobile for Smartphones.
And so are Playbuntu (new), Ubuntu Studio, Fluxbuntu, Ubuntu Server, and more.
But we will only talk about the 3 most important ones (Ubuntu, Kubuntu and Xubuntu).
And so, Ubuntu uses GNOME, Kubuntu uses KDE, while Xubuntu uses Xfce.

GNOME? KDE? Xfce? What are those?
Those are diffrent GUI's.
Like GNOME, GNOME has mostely 2 bars, top and button, and it has more cartoonish graphics.
GNOME is the best graphical interface, in my option.
KDE uses a graphical interface, simular to Windows XP with the classic interface.
People who have used Windows in their entire life and want to change to Linux, I'll recommend to use KDE.
Xfce is the graphical interface you saw in the most tutorials at Nintenlord.
Xfce is based on GNOME.

Well, let's see what Ubuntu will fit you most.
Question 1: Did you use a Mac, and do you like it?
GX. Yes.
K. No.

Question 2: Do you have an old computer, or a very slow Windows computer?
GK. No.
X. Yes.

Question 3: How old are you, and how technical are you?
GX. I'm young and very technical.
K. I'm old and not technical.
G. I'm young and not technical.
X. I'm old and very technical.

Question 4: What colour do you like most? (Dumb question)
G. Red and a little orange.
K. Blue.
X. Gray.

Question 5: How much do you like sound effects?
G. Very clear, musical sounds when starting up and shutting down.
K. Sound effects? Lol! Who freaking cares?
X. Don't know, as long as my system makes sounds, it's allright.

Question 6: Who are you?
G. Someone that wants a very cool computer.
K. Someone that wants a very easy computer.
X. Someone that wants a very fast computer.

Question 7: Do you liek Mudkipz?
GKX. Yes, I liek them!

If your most answers are G, then Ubuntu suits you the best.
You want a cool PC, your PC is new, you like red and your sound effects are crystal clear.
If your most answers are K, then choose Kubuntu.
You want an easy PC, your PC is new, you like blue and you have no sound effects.
If your most answers are X, Xubuntu wants you.
You want a fast PC, your PC is old, you like gray and your PC is making noice.

My choice.
I have choosen for Xubuntu, because my laptop is not strong enough for Ubuntu or Kubuntu.
But my future laptop will be Ubuntu, I like Ubuntu the most of all Ubuntu's.
My sister has choosen for Ubuntu.
To know why, email her (Dutch only). :P