Installing Xampp and WordPress

First go and download XAMPP Lite from http://www.apachefriends.org/en/xampp.html. You can choose a larger package if you need, but for WordPress, the Lite package is fine.
You can choose one of two download packages - the ZIP or the EXE. If you are unsure, choose the EXE as this will install itself. (The EXE is also smaller).
Move the downloaded EXE file to the root of the drive. In my case, this is C:\

Double-click the file and the extract dialog will appear

Click extract - and wait a few moments while it does it's job.
You will then have the xampplite directory at root

Now you need to start Xampp.
Open the xampplite folder.
You should be seeing a screen with these files (among others) on

Click "setup_xampp.bat"

Once you have the success message, you can click "xampp-control.exe"

Now click both indicated buttons to get xampp working in the way we need

Now you need to see it all properly.
In your browser, enter the address http://localhost/xampp/splash.php

After you have clicked your language and entered the program, click phpMyAdmin.

Copy exactly what is in this image and press Create.

That is xampp completely sorted out for now.

Download and unzip WordPress.
Open the file wp-config-sample.php
These are the exact details you need for Xampp to work because the default user in phpmyadmin is called 'root' and there is no password.
define('DB_NAME', 'wordpress'); // The name of the database
define('DB_USER', 'root'); // Your MySQL username
define('DB_PASSWORD', ''); // ...and password
define('DB_HOST', 'localhost'); // 99% chance you won't need to change this value
Copy those details into your wp-config file, and save it as wp-config.php

Now you need to copy the files to the right place.
Click the Start button, followed by My Computer > Main drive > Xampplite > htdocs
Copy the whole WordPress folder into this directory.

In your browser, go to http://localhost/wordpress/wp-admin/install.php and everything from there should run smoothly !

NOTES:
You do not need to use the inbuilt editor to change any WP files. Just open them directly in your text editor, make your changes and then save. As there is no uploading to do, it makes things much much faster - and you can do this without an internet connection too.
If you want to use permalinks, you will need to make a change inside another file:
Click the Start button, followed by My Computer > Main drive > Xampplite > apache > Conf and find the file httpd.conf. Open that in a text editor. Use the search facility in the editor to find "rewrite". The line you need looks like this:
#LoadModule rewrite_module modules/mod_rewrite.so
You need to take away the hash sign so it looks like this
LoadModule rewrite_module modules/mod_rewrite.so
Now just save the file.