I don't know but I think that right-click pop up is called a "context menu" so that might be a term to search for. Seems like I used to know how to customize it but I cannot remember how.
My first thoughts were to look in Taskbar/Start Menu properties and Folder Options (via Control Panel in XP) but I can't find anything in either that looks like what you would want.
Well it is customizable to some degree in Tweak UI for XP, if that's your OS. If you don't have Tweak UI it was one of Microsoft's so-called "Power Tools" for Windows, the XP version was available free from the Microsoft site cuz I had it at home and still have it here at work.
http://windows.microsoft.com/en-US/w...ads/windows-xp
Under "My Computer" and "Templates" it has a list of possible document types that can be created from the "New" command on the right-click popup menu, and you can select or deselect them to get them on or off that menu. So obviously it's doable but I don't know how without using Tweak UI.