I will take a shot at this. The main question should be what is the difference between Ubunto or Kubuntu and Windows.
Ubunut and Kubuntu are basically the same. They both have Linux underneath. But the window manager and desktop environment (what you see when you log in to your account: the windows, the menus, the panels, etc.) are different. You could install either Ubuntu or Kubuntu, the only difference will be in the look and feel of the desktop. Installation process should be similar in both cases. Ubuntu uses Gnome as the default desktop and Kubuntu uses KDE, the two most popular featureful desktop environments in the Linux world (there are many others though). Lastly, no matter what one installs, Ubunut or Kubuntu, it is very easy to install the other desktop env. afterwords (install Ubuntu first and then add KDE to it, or install Kubuntu first and then add Gnome to it).
Now, difference between Ubuntu and Windows. They are different fundamentally, they are different operating sytems. If a computer machine already has Windows on it, that is why one would need to find a separate parition on the hard disk to install Ubuntu on.
Some tips:
- On a desktop, easiest method is to add a new hard disk (or empty an older one) and install Ubuntu on that.
- If there is only one disk (laptop or desktop), one needs to create a partition to install Ubuntu on.
For the latter choice above, the Ubuntu installee will help you do it during the initial installation steps -- you do not need to do anything special before hand other than save all important data in case something goes wrong (not that it will, but precaution is better than cure).
Installation itself is quite easy, no where as difficult as a Windows installation. In fact, once you are past the stage where you choose the installation disk or partition, rest is all just a few clicks away.