Can I safely reformat an empty partition to reclaim "used" space?

[FreshFrost]

My laptop came with a single SATA HDD that was partitioned into a C:\ and a D:\ drive.

I haven't used my D:\ until now that my C:\ has filled up. Once that happened, I dragged and dropped the 'My Documents' folder into the D:\ drive - then thought better of it, dragged it back into C:\ and came onto a forum for advice on how best to go about it.
Before all this action, the D:\ was always shown as having "Used Space: 0MB, Capacity: 72GB". After all the dragging-and-dropping to and from C:\, however, D:\ supposedly has "Used Space: 192MB, Capacity: 71.8GB".

I tried to return D:\ to its completely empty state by clearing it out, viewing and removing hidden files, using Disk Clean-up, running Defrag, etc. But it still shows as having "Used Space: 192MB, Capacity: 71.8GB"!

Why is this?
I mean, I know that amount of usable disk space is not always as advertised, but how come D:\ used to be able to to show 0MB used space, but now has to show 192MB used space even though it is just as empty as before?!

So now I'm thinking of reformatting D:\.
But since D:\ is just a partition within a drive, won't reformatting it affect my C:\ as well? If so, how?
Are there any (other) dangers to re-formatting the D:\ partition?
How do I even go about reformatting just the D:\ partition safely? (I really don't want to touch C:\ ...)

Finally, is there any other way that I can 're-claim' those 192MB?
(I know 192MB isn't much compared to the 71.8GB I've got left, but it's still a good 2 or 3 music-album's worth of space ...)

Thanks in advance! Any help is much appreciated!

Edit:
Bw, the defrag analysis offered the following info:

Volume ACERDATA (D
Volume size = 72.04 GB
Cluster size = 4 KB
Used space = 216 MB
Free space = 71.83 GB
Percent free space = 99 %

Volume fragmentation
Total fragmentation = 0 %
File fragmentation = 1 %
Free space fragmentation = 0 %

File fragmentation
Total files = 108
Average file size = 2 MB
Total fragmented files = 1
Total excess fragments = 6
Average fragments per file = 1.05

Pagefile fragmentation
Pagefile size = 0 bytes
Total fragments = 0

Folder fragmentation
Total folders = 13
Fragmented folders = 1
Excess folder fragments = 0

Master File Table (MFT) fragmentation
Total MFT size = 12 MB
MFT record count = 136
Percent MFT in use = 1 %
Total MFT fragments = 3

(things in bold are by me)

This just reiterates my question tho:
What and where are those 108 Total files and/or 13 Total folders?

[ctal]

Hi Francesca --

There is no problem at all reformatting the D partition, and your C partition will not be affected. Partitions are routinely formatted independently of one another. The most convenient way to do that, assuming you have Windows XP, is to use its Disk Management utility. That is under Control Panel\Performance And Maintenance\Administrative Tools\Computer Management\Disk Management (if your Control Panel is set up to display icons instead of text on a blue background, ignore the reference to "Performance and Maintenance"). Right-click on the D partition, select "format," and follow the prompts. You will want to select the NTFS file system, rather than FAT32, first because it is superior in many ways, and also because I believe XP cannot format a FAT32 partition larger than 32GB.

I think the reason for the persistent 192mB indication might be that the master file table for the D partition expanded when you put My Documents on D. I don't think XP's defragmenter can compact the MFT (other defragmenter programs can), but in any event that will be resolved when you reformat.

Regards,
-- Al

[ctal]

I wrote the above before seeing your edit. Not sure what all of those files and folders are -- check the "system volume information" and "recycle bin" icons for D, under My Computer, and see how much if anything they contain. In any event, I wouldn't worry about it assuming you are sure you have moved all of your own data back to C.

[k0NG0]

Think of partitions as slices of pie. Your hard drive is a pie, and by chopping it into slices you get partitions. Formatting one partition (eating one of the slices) doesn't affect the other partitions (they're still there in their pie-y goodness).

For this particular question, I think that's a good analogy.

[Bofinn]

And when you eat the slice of a pie, there are usually some crumbs left in the bottom of the pan...