You can still type 'sys D:'. Use a DOS window or the 'Start-->Run' menu.
I did something similar when I got a new hard drive for my laptop. And got to do it all over again when the new drive failed after 9 months... <img src="frown.gif" border="0">
Basic procedure:
1.
Make a bootable floppy before doing anything AND back up your data!!!!.
You will also need a DOS disk partioning program. Put a copy of it on the boot disk in case things go awry. There's plenty of them available for free. I have one I can send to you (if I can find where I put it!).
Make sure both drives are connected & readable/writable.
2. Format the new drive.
Don't set the intended Windows partition to 'active' yet ie informs the operating system which partition to boot from.
Windows has a right hissy fit if it finds more than one active partition eg one on each drive
3. Type 'Sys D:'
4. Copy everything else to the new drive. Don't forget hidden files.
5. Using a suitable disk partitioning program delete the 'Active' flag on the OLD disk AND set the 'Active' flag on the NEW disk.
Note: The disk partitioning program can be resident on one of the HD. It gets loaded into RAM before it can be used.
6. Shutdown & swap the cables between the two hard disks so that the new disk becomes 'C:' & the old disk becomes 'D:'
7. Reboot and all will be well with the world, millions will be saved from starvation, war & pestilence, pollution will disappear, old growth forests will reappear, as will numerous extinct or threatened species, beautiful & ethereal music will be yours to behold etc etc etc...
Alternatively armageddon just knocked on your door.