Is there any way to turn off the warning you recieve when changing an extension on a file or folder?

I have to do this several times a day and it is annoying.

I know that most probably don't run into this issue, so let me explain.

We receive art files from a customer to go with a job they want created. When we have created a workorder for the related files we enclose them in a folder and rename the folder with the workorder number such as WO4444.sit and then email the compressed folder to our art department for processing. The .sit part of the naming is where the warning comes in, because an extension is being added. The warning provides me two choices - one to add the .sit or to cancel. And of course the action that I want to take is not the defaulted action. This requires a mouse move and selection to select the add option. I know this sound whiney, but when you have to do this about 30 times a day, it just adds frustration to an already hectic environment.

The .sit activates stuffit compression automatically at least on a G4 machine - doesn't work on an intel, on intel you have no choice but to use the right click contextual menu, but I digress.

I know that I can right click and compress via the contextual menu without the warning, but I am just trying to avoid an extra step when I have to rename the folder anyway.

Any thoughts?