size of files

i asked for the properties of all my files of my computer and got this
size 81,0 GB (87.002.311.232 byte)
size on disk 75,5 GB (81.082.171.782 byte)

how on earth 81,0gb of data is stored in 75.5 gb ??? thats 5.5 gb less
the normal would be too be something like 5 gbyte more due to slug the unused space in a sector. is this an error of the windows??
windows xp pro sp3

 

Do you see a lot of files and folders colored blue in Windows Explorer?

If so, you have a lot of compressed files. If you have compressed the entire drive, it can slow your computer down because it has to utilize resources decompressing everything before it can read it.

 

So, you have an "80GB" hard drive, right? And, it's 100%, or nearly 100% full? Does this seem realistic to you, based on what programs and user files you have on your hard drive?

 

THe hard drive is 200gb. I have 125.000 files. Well given i have 2-3 backup of the whole operating system windows folder i could say it is realistic to have so many files. But no i do not see and blue files on my hard drive. nor i have compressed ones. i have a few winzip file but i do not think that count towards that, nor are so big to make the diferense. windows by default compress files??

 

Windows Update and Service Pack files are compressed by default, this could be the discrepancy you're seeing. You won't see them unless you unhide all files in Explorer.