How to add a notepad entry to the file right click menu

Be forwarned: this node will require knowledge of how to work a mouse, a keyboard, and the start menu.
I suppose that if you don't know what you are doing with this, now would be a good time to stop, since this could quite possibly have evil consequences that I am unaware of.
I am not responsible for setting your computer on fire.

Start by opening regedit.exe, the registry editor that comes with Windows.
Expand HKEY_CLASSES_ROOT, and select the entry labelled '*', it should be at the very top.
This entry defines actions and things that are relevant to all file classes.
Expand *. Right click on the * folder icon and create a key, call this key "shell".
Select the newly created shell key and create another key below this one, call this "edit". Select the edit key, and change the default value to something appropriate. This value is the description that will appear in the menu when you right click on a file. "Open in &notepad" would be a good choice, the n will be underlined, signifying that you can press the n key to do this.
Now create a new key under edit, call this "command", and change the default value in this key to "C:\WINDOWS\NOTEPAD.EXE %1".
This can also be adapted to work with any other program you'd like it to, by changing which program the key runs, i.e. "C:\mplayerc\MplayerC.exe %1"

Hooray, now you can open any file in notepad simply by right clicking on it and selecting notepad.
Yes, this is very useful.

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It has come to my attention (by trying to implement this in Windows XP), that it won't work in XP. It is, however, still relevant to those who are using the versions of Windows that it works on.

Alternatives for those not wanting to mess with the Registry:
a) Add a shortcut to Notepad (or whatever) to your 'send to' folder: C:\WINDOWS\SENDTO.
This shortcut will now appear in the 'Send To' menu that appears when you right-click on a file.

b) If you just want to be able to edit particular types of files (eg .dat) in Notepad, then you can add 'Edit in Notepad' as an available action for that file type.
To do this:
- open windows explorer, and select View | Options from the menu
- select the File Types tab
- select the file type that you want to edit in Notepad, and click Edit
- click New and a 'New Action' window will pop up
- enter your action name in the first text box, eg 'Edit in Notepad'
- enter "c:\WINDOWS\NOTEPAD.EXE %1" (without the quotes) in the second text box, and click OK
- click OK to close all windows
- you're now the proud owner of a new right-click menu option when you click on files of that type.

But the registry way has the great advantage of working for all file types!