How to unlock a Microsoft .docx document? – Super User

DocX is a compressed zip container file. Make a copy of the original docx file. If you unzip it, there is a subfolder named word with a file named settings.xml. You can open settings.xml with a plain text editor.Within that there is a block of text:

<w:documentProtection
w:edit=""
w:enforcement="1"
 w:cryptProviderType=""
 w:cryptAlgorithmClass=""
 w:cryptAlgorithmType=""
 w:cryptAlgorithmSid=""
 w:cryptSpinCount=""
 w:hash=""
 w:salt=""/>

You can either change w:enforcement value to 0 or remove the block

Source: How can I unlock a Microsoft .docx document? – Super User

how to dual-run Office XP/2K3 and Office 2007

To run both versions of Office 2002/3 and Office 2007 on same machine:

  1. Set the file-types to open with relative version of Office: .doc, .docx, etc.
    (i.e. set .doc to open with word 2002 and .docx with 2007)
  2. Open Regedit
  3. HKEY_CURRENT_USER\Software\Microsoft\Office

For Word 2007:

  1. \12.0\Word\Options
  2. create a new DWORD value and set it to 1

For Word 2003:

  1. \11.0\Word\Options
  2. create a new DWORD value and set it to 1

For Word XP/2002:

  1. \10.0\Word\Options
  2. create a new DWORD value and set it to 1

Credits to: Geoff
http://www.gearfire.net/run-office-xp-office-2007-computer/