Would be great if someone could help me with this. I am running windows vista ultimate, my c drive is 29.2 gb and i have 7.86 gb free which means i have 21.34 gb used but when i actually total up everything on the c drive it comes to 17gb. So there is another 4gb somewhere that i cant see, that is not showing. I have made sure that all hidden files are visable and ive totalled it up several times now and it always comes to 17gb! i just cant seem to account for this 4gb. Any ideas at all?? Thankyou

System protection and also hibernation will take some space up if you do not need them do not use them. To get rid of hibernation go to program files, accessories, and then disk cleanup. Should give you a option for hibernation. The other use the following guide. http://www.howtogeek.com/howto/wind... Jim R

Thankyou very much, very useful Nick

Are you totalling the actual file size of the space the file uses up on the disk which is not necesserily the same. On the NTFS files system files always take of a multiple of 4 kBs. This is the cluster size. So even of 1 kB text file will take up 4 KBs of disk space. A 6 kbs file will take up 8 kBs of disk space. The difference is known as slack space. With FAT32 the differential will be even greater. Stuart

In addition to what StuartS said you have a page file that is reserved but not fill with anything. If you wish to know the purpose of the page/swap file Google for it. Also, the recycle bin will use space that doesn't show as files until you empty it. To see the size of the page file Right click on My Computer and choose properties> advanced> performance settings> advanced. The page file is listed as Virtual Memory.