Word 2003: File Needs To Be Opened By Text Converter

A client of mine was getting a most annoying pop-up when trying to open a Microsoft Works 4.0 (.wps) file in Word 2003. The message was:

This file needs to be opened by the Microsoft Works 4.0 text converter, which may pose a security risk if the file you are opening is a malicious file. Choose Yes to open this file only if you are sure it is from a trusted source.

The Microsoft knowledge base article suggested I install service pack 3 to resolve the problem. It didn't! I had to apply the registry fix they suggested. Having done that, the warning is removed. This is the registry change required (taken directly from the article):

1. Quit Microsoft Word.
2. Click Start, click Run, type regedit, and then click OK.
3. Locate and then click to select the following registry key:
   HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Word\Options
4. After you select the key that is specified in step 3, point to New on the Edit menu, and then click DWORD Value.
5. Type DoNotConfirmConverterSecurity, and then press ENTER.
6. Right-click DoNotConfirmConverterSecurity, and then click Modify.
7. In the Value data box, type 1, and then click OK.
8. On the File menu, click Exit to quit Registry Editor.