Goodbye semi-important data

So, explorer's acting up and my sound is so messed up that I decide to do a fresh install of w2k.

I'm about to do it, but then remember I need the sata drivers. So I download the latest ones from nvidia, copy them on a disk and off I go. Everything goes fine until every updates are installed (sp4, dx9, etc).

That's when I noticed that even though w2k was seeing my whole 200gb drive, it wasn't seeing the partitions beyond 137gb. Instead, that space was seen as free space. There were supposed to be a few logical drives there, not free space.

I downloaded and tested a few free data recovering tools. One of them was File Scavenger 3.0, and although it didn't find the files I wanted it to, it did find a ridiculously high amount of ridiculously old files, including files on areas which had multiple partitions created/destroyed, so I was impressed by that.

Is it possible that because I went from XP to w2k and that I used newer sata drivers for the install that the partition I wanted to keep was simply colateral damage ? So much that it's the only part of the drive where no deleted files were found ?

The files weren't that important, but I'd like to hear some theories.