Advice about Win 7, Disc Management

Disk management will not expand a partition except into contiguous (physically adjacent) unallocated space, so if your C: and D: partitions are next to each other on the disk, you will need to move the starting location for that partition over so that the space between end of C: and beginning of D: is as large as you need to expand your C: drive and is unallocated i.e. not formatted, and not even included within a partition. Having accomplished that, Disk Managment can expand the C: partition into that unallocated space. So yes you will need to shrink or delete the D: partiton to expand the C: partition, and the process must create the new unallocated space between the C: and D: partiton. Disk management can shrink a partition limited by the partiton free space (no data) and the location of immovable files on the partiton.

i wrestled with this a couple of years ago and determined that the easiest thing to do was to buy a new drive and install the OS and software I needed.  You could also make an image of your C-drive and copy that to the new disk.
 
The lesson I learned is that partitions are usually more trouble than they are worth.
 
if you do try to move the partitions - good luck.

BbAltered
 
It might be easier for me to delete my D: partition, expand the C: partition as needed, and then re-allocate whatever space is left over into a new smaller partition.  But by now, I have data files (samples and such) in the D: partition that other programs are using.
 

 
I think that by default shrinking your D: drive will produce unallocated space that is not contiguous with C:, but will appear in the bar graph to the right of D:. So yes the easiest way to control the new partition would be to copy the D: partition data (using a copy process that preserves the directory structure of D:) somewhere else where you have room, then delete the D: partition, then expand the C: partition into the unallocated space left by deleteing D:. You can then set up a new D: partition in the remaining unallocated space, or any other location that has unallocated space. During the format phase of creating your new partition you will be given the option to assign a name to the new partition, just call it D:, and all of your existing data from D: can then be copied back onto the new D: disk and your programs will all be able to find it where they expect it to be. You can even if you like make a new directory entry in one of your other partitions  name the directory something you will recall (E:\vDisk1 say) and then create a virtual disk (a data file that looks like a hard drive to Windows)  and name the virtual disk D: and it will have the same result as recreating a normal D: partition as far as the software that is looking for its data on D: is concerned.  
 
http://www.howtogeek.com/howto/5291/how-to-create-a-virtual-hard-drive-in-windows-7/
 
To attach the virtual hard drive automatically at startup:
http://www.overclockedtechies.com/2012/02/attach-vhd-on-startup-automatically/
 
 
 

SuperG makes a good point, if all you need is more space on "Drive C:" you can do it by mounting a directory on another drive or partition to extend the C: logical drive to that location. You could achieve a similar effect by using links. These methods may require some special handling in making disk images or backups that work the way you expect them to, so be careful.
 
http://www.sysprobs.com/e..d-drive-windows-7-space
 
http://www.sevenforums.com/tutorials/278262-mklink-create-use-links-windows.html