What issues have people encountered with older OS's (2000, XP) and olders versions of Microsoft Office (2000, XP, 2003) with the 'Microsoft Office Compatibility Pack'?

I have a couple of Windows 2000 client PC's encountering different errors when attempting to open .docx or .xlsx documents, some with Office XP and the others with Office 2003.

Reading through forums it appears that the different versions of the compatibility pack, not all were compatible with Windows 2000 (versions 3 & 4 are not). There are also Service Packs for the Compatibility Pack. With these Windows 2000 clients, it seems i need the Compatibility Pack version 2, then to install the Service Packs, yet i'm unable to find a link for version 2 of it.

First error message:

"This is a pre-release version of the Compatibilty Pack and can open pre-release Office 2007 files only."

Is solved below.

Second error message:

"The converter failed to open the file."

My troubleshooting is still on-going.