Windows documents - text loss - can anyone help?

This past weekend I downloaded Rapport anti ID theft from Natwest online which claimed to be compatible with Vista (I have an Advent 8117 laptop and use a LaCie Mobile Hard drive).
Come Sunday morning, I tried to opena document on the mobile hard drive and discovered that it wanted me to install "Microsoft Office 2000 premium" - but worse it opened what should have been a 4-page document as "0kb" - 4 pages of typing had disappeared, though the document file itself remained.
For some reason the LaCie hard drive has randomly gone through folders wiping off the text from some MIcrosoft word documents and not others. Some files were 50+ pages long Microsoft Word Documents that have just gone. The drive lists the file as being present but as "0kb", yet other documents are unaffected - for example, my novella "Having A ball" has chapters 14-22 as 0kb, chapter 23 is fine, Chapter 24 is blank again and Chapter 25 is fine?!
I have sent the mobile drive to a specialist data retrieval company who have scanned it but are not hopeful - sometimes Microsoft has multiple files of documents stored but it seems most of my documents - over 20 years of work in some cases - have had the text wiped off.
How can this be? Every day papers quote experts telling us we cannot escape data retrieval unless we take a hammer to stuff, how can straightforward typed text in Microsoft Word be simply wiped away like a wet cloth across a smeared window? Can anyone suggest any way to get the text back? Has anyone had similar problems with rapport? I cannot believe - or cannot give up hope - if I were a criminal mastermind who'd done this deliberately surely there would be someone stepping up the plate with a "not so fast!" and the stuff to retrieve the typing? Any help would be tremendously appreciated - this has been devastating for me; I feel physically ill and have been shaking like a leaf for most of the week since Sunday. I cannot believe Natwest allow this download to go ahead unless they are sure there are no bugs in the system.

What version of vista have you got? Ultimate keeps shadow copies afaik.

Hi, thanks for response - er, I bought the laptop (Advent 8117) in December 2007, so whatever was the current version of Vista then is what the laptop is.
The laptop is actually not a problem now becuase I uninstalled Rapport immediately and system restored it back to 26th march, but of course that didn't fix the LaCie Hard Drive.
I just get so upset when I read all these vaguely threatening news articles where all these self-styled but carefully anonymous "experts" keep saying that they can recover any data from anything, but I'll love to give them the chance to put their money where their mouth is.

Talking about this; www.noisp.me.uk/previous.jpg . It's a long shot anyway as you'd have had to have done a backup first. There's a lesson in here about keeping backups somewhere, but you know that by now I'd imagine.

I don't see how a program like the one you installed could of done the damage tbh, sure is weird. Sounds more like something a prank virus would do.