Tony,
No, I have never used Partition Magic.
I have not had the need to spend the money for the utility, as I always have spare HDDs on hand.
Of course, the fact that they warn you to back everything up first is a concern.
I suspect that youwill need to perform what you want to do in stages.
Start by clearing as many files as possible off of the D: drive.
Shrink the D: drive down in size, and allocate the free space to the C: drive.
Continue until the D: drive is gone.
Now, the E: drive will be the D: drive, and you will need to follow the same sequence to move the drive over to C:.
I setup all systems with at least 1 logical drive.
I copy the Windows CD, and ALL downloaded drivers onto this drive to ease recovery from crashes.
I then move virtual memory over to the extra drive to reduce file fragmentation, and scandisk / defrag restarts.
There is a good article on partition stratagy posted at www.aumha.org
When I upgrade, I usually include a new hard drive. I just mount the old drive as a slave, and copy over what files I need, or I use my hot swap bay, and back things up on CDs.
I am a firm believer that a fresh clean install is ALWAYS better than an upgrade install.
Yes, you need to re-install applications, but you start out with a much smaller registry file than you get when you upgrade, and that does boost system performance quite a bit.
Another side thought.
If you have any application software loaded onto the logical drives, you will need to either update ALL the pointers for the software (including the registry) or, re-install the software anyhow.
Chas