DriveCleanser - what exactly does it 'delete'

I used DriveCleanser to clear a 660gb D: drive on my 2-day old 750gb Seagate Momentus XT because I wanted to go for a single big C: drive.

I thought it would only remove the data but no tool I have used (Windows Computer Management, Acronis, Seagate Tools & HDAT2, all in several different laptops) seems to be able to get the 660gb space back, so my fairly expensive disc now only has 73gb capacity, less than the drive I bought it to replace.

So the question is, am I a numpty & because I thought DriveCleanser only affected the data on the drive, or has DriveCleanser actually told the disc it's now only 73gb & set a password to prevent it being reinstated. (HDAT2 can see the disc is 750gb but tells me the disc password-locked so fails to reset the capacity)

Thanks!

Christian.