My hard drive is partitioned into C, D and E.

C has 27.65 GB
D has 24.87 GB and is the Backup
E has 3.39 GB and is FAT 32

I have 23.4 GB free on D which I do not use because the drive is the system backup. I only have 1.21 GB free on C. Can I reduce down the amount allocated to D and transfer it to C or am I stuck with things as they are?

You cannot do this from within Windows but you can use partitioning software.

There are several commercial products out there but I use GParted which is free.

Is it simple to use and I mean simple? I know it is probably asking a bit much but is it foolproof. I have an external drive so could free up some space by archiving some of my image files if that is a safer option than doing this. My computer is my livelihood . . .

If you cannot do this from within Windows do you still run GParted from Windows and are you able to back out of GParted if you are not sure about what you are doing?

GParted is included in most Linux Operating Systems. The link I posted is a Live CD version. This is an ISO download from which to create/image a Boot Disk. It is a self sufficient tool that boots outside of Windows.

I find it easy to use and there are several guides plus a forum in the Documentation section of the linked site.

I don't think anything is "foolproof" or 100% guaranteed but I have never had a problem with it. If I had critical data I would have it backed up anyway.

GParted will boot and run but will not do anything until you confirm all the options you choose. It that sense it is fairly safe. You will be asked a few times if you are sure you want to do what you are doing and you can always close it without doing anything.

It occurred to me that I am over complicating things.

Rather than repartitioning the drives all I need to do is use drive D (which is where the system back-up is located) for additional storage of stuff I don't use so often. Just create one new folder called "Storage" and put everything in it.

That should not cause any problems or risk messing things up. Am I correct?