There's no doubt that the path mentioned (Tools|options|General Tab|Service Options button|Online Content category) will prevent the Templates Help from appearing on your own computer.
What I was looking for, however (and couldn't find anywhere) is to prevent Templates Help from opening when a spreadsheet is opened - no matter who opens the file! See, I wanted to hide the fact that I used a template from Microsoft to create the spreadsheet. (Sure, I'm sneaky, but hey, I'd rather they think I spent hours making the thing.
Here's how to do it:
With the spreadsheet open, close the Templates Help.
Click on File, then Properties, then the Custom tab, then click on the word Template in the Properties window, then click the Delete button.
Save the file.
Now, no matter who opens this former template file, they will never know that it was once a Microsoft template...
