How do I re-install software that came pre-installed on my mac?

Question

How do I re-install software that came pre-installed on my mac?
I bought my first mac in 2003, in 2004 I bought MS Office: Mac. In 2006 I got another mac, this one (I'm pretty sure but not 100% certain) came with MS Office pre-installed. I'm still using that computer I got in 2006 (writing this message on it right now) and have been having problems with Word and have had no luck with trying to fix it. I recently came across my original installation disk for the version of MS Office I got in 2004. So, when I became frustrated trying to fix Word I just grabbed this old installer and reinstalled office, assuming in that moment that it was the same version I had been using. I got it all installed and working and went to load up my most recent document that I've ben working on and it won't load because it's a docx file. I don't know where else I would have gotten a new version of word, I'm not one for unnecessary updates and updating a word processor is about as unnecessary as it gets. I MUST have had a newer version of word pre-installed on my computer, because any time I've ever tried to open word files from this computer on my older mac the files wouldn't work, so any time I need to do that I either make a PDF or email myself the text.
Anyway, I'm assuming that apple has all my registration info on file and can confirm that I bought the software, can they provide my an installer? My other concern is that this computer was a christmas gift and was purchased by my dad, though I don't know whose name is on any kind of registration that may exist. The problem here is that he died, so I'm concerned that apple won't support my product because the original "owner" is deceased, even though I don't think he ever so much as laid a finger on this computer or even looked at it more than twice after he gave it to me.
What is my best course of action here?

Answer 1

I would have to presume the 2006 Mac was used, and came with Office 2008 on it from the seller. Apple has never offered Office as a bundled purchase, and it is not pre-installed with any Mac.
Since you have the disk for Office 2004, the activation key should be on a sticker on the CD/DVD sleeve. As I recall, anyway. I no longer have my 2004 copy to check. If you have the key, it doesn't matter who it originally belonged to. You can still enter it and activate the software.
Once you have that installed, you can install the XML converter for Office 2004. That will allow you to open from all newer Windows and Mac versions of Office. The only things that won't necessarily convert are features that don't exist in Office 2004, and so can't be translated correctly, or at all.
Microsoft is saying Office 2016 for Mac and Windows should be available for the official release sometime either late summer, or early fall. So hold off purchasing a new version if you can. MS offers to reduced upgrade price for Office. You'd pay full price for Office 2011, and then again for Office 2016.
And just to note. Office 2008 and Office 2011 work fine in Snow Leopard.