How to open docx in MS Word 2003

Docx is a new format in MS Word 2007 and later, so by default MS Word 2003 is unable to open and edit documents in docx format. Personally, I am reluctant to use MS Word 2007 and later, because its design is far different compared to previous version of MS Word. Users should familiarize themselves to new design in MS Word 2007; this is my main reason not to use it as replacement.
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There are two methods to open docx in MS Word 2003:

1. I installed MS Word 2007 side by side with MS Word 2003. Afterwards, MS Word 2003 is able to open docx without problem. I still prefer MS Word 2003, but installing MS Word 2007 can make us more familiar with MS 2007. 
2. Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint File Formats. This plugin enable MS Word 2003 to open docx (and MS Excel 2003 and MS PowerPoint 2003 to open xlsx and pptx respectively). Some windows updates are required to install this program. 

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