You can't rename a drive that is running an o/s on it. So D stays D. The only way out of this is to do what I did...unplug that drives until you are formatted, forcing your computer to make that drive your C drive.
I have a SATA with an O/S on it so it's still unplugged but I have a 30 gig and a 160 gig that are regular IDE's. As long as the 160 gig was plugged in, my computer would be stupid and regardless of how hard I tried, it would NOT let me name the 30 gig the C Drive, so I got even and unplugged it during the format, LOL.
Well, with only ONE drive plugged in, it had to be the C Drive. I formatted and the first time I shut down, I plugged my 160 back in and voila, all the drives are back like they reasonably belong. I still haven't decided when to deal with my SATA cause I prefer to keep my O/S on my smallest hard drive. But I have it there and can force the issue. Liz