Quote: "Is it actually reducing the total amount of space like say, an 80 gig would be 76 gig the next day?"
Yes.
Quote: "or is it filling up with some type of data?"
I don't know.
I know there are all sorts of hidden system files containing backups, temporary files, restore points, etc, and also files associated with Windows updates (the PC has been busy installing these since it was set up). But I doubt this would explain 4GB a day.
Quote: "I'd say bring it back and ask about it. That does not sound good at all, as I said it could be that you just got a bad hard drive."
That's my main fear.
Quote: "Is the drive filling up? (i.e. the number of files is increasing, space decreasing) or is Vista reporting a smaller overall drive size each day?"
That's part of the problem - how do I find out easily? Vista merely reports several folders as being in excess of a certain size -how can I find out how big they really are?
Quote: "If the later I'd get that drive RMA'd immediately!"
I might if I knew what that meant.

Could you elaborate/explain?
Quote: "If the first one I'd place good money on it being a rogue application / service you've got install that is doing it, rather than Vista itself."
I hope so - but don't really know how to proceed.
I don't suppose DBPro could be the rogue, could it?
It would be good to get this sorted out fast before I get too much installed.