Efficiently change a single file extension in Windows

What is the simplest way of changing a file extension (without messing around with folder view options)?

Oftentimes I have to quickly change the extension of a single file on a Windows PC. I don't like to turn on the option to show file extensions, change the extension, and then turn the option back off. If I forget to turn off the option, the client will not understand how his computer works; this method also involves a lot of clicking. What is the fastest way to change a file extension?

Update
For completness, here the fastest way I have figured out until now:

• Right click in the folder while holding down the Shift key.


• Select Open command window here from the menu.


• Use dir to list the currrent file name with its extension.


• Enter rename [filename].[oldExtension] [filename].[newExtension].

Answer

You could try cmdHere (Power Toys) and then using move filename.jpg filename.jpeg. Or you could Press F2 for rename (If it works with disabled extensions!).

But you should enable extensions anyway. As i would think it is a security risk to have them disabled. An attacker could send you an file like "Really Important Filename".exe With an standard icon included in the .exe making it look like an Word, Excel or Text Document. You might then click it unaware of the .exe file format. THIS is an EVIL feature of Windows.