So now. If 300GB is actually in reality 279GB. How can 500GB result in 232.87 GB?.
It doesn't. Looking at the image I see one 500GB drive being listed as 5.59GB+74.50GB+152.78GB+230.42GB+2.46 =465.75GB. There is only one physical Hard disk drive being detected and shown by disk management. the 250GB drive is not there. the near 250GB partition is the result of you cloning the 250GB to this 500GB. No idea what you did with it after. Either you removed it (in which case you are silly for thinking that you can remove it and still use it) or you didn't swap about the new drive with the old properly. Connect the 250GB as a slave drive. It will still have the same data as before. You can wipe it however since it is now cloned to the new drive.
But consider this, if you look at my png.file, my 250GB drive totals to 232.89GB
No. Your 250GB drive is not even in disk management. only the 500GB is. each physical drive is shown as a separate item. (Disk 0, Disk 1 in my case for my two physical internal hard drives). You only have one. the 232.89GB
partition (NOT drive) is the result of when you cloned XP from the 250GB. Wither the 250GB is I don't know. As I noted you may have removed it for whatever reason, or it could simply be connected improperly (I'd bank on the latter).
But for my 500 GB to only realize 232.87 GB (this is less than the 250 GB drive)
All of the listed partitions reside on the 500GB drive, a total of 465.75GB. No 250GB drive is in the disk management image; there is a 232.87GB partition on the 500GB drive, but that doesn't magically give you extra disk space, nor does it have anything to do with the 250GB; which doesn't even show up in the upper list so is not being detected by the computer/Windows to begin with.