Program that lock and hide folders and shows the hard disk space same as before

Hi
I am looking for a Program which can hide and lock my data and shows the hard disk space same as before.
For example, I have made a partition which is of 100GB and some files inside the partition are very private and these files hold a size of like 12GB.I actually hide those files but when my friends come in my house, they start to look in my Computer's harddisk. They look at the Properties of Partition, Calculate Used Space and Total space and they find out the space hidden and ask me to show the Content which i am hiding.

I know there are folder hiding and encrypting softwares like Folder-lock, AEP, TrueCrypt but i am looking for Softwares that hides DATA and when looking at the space of a partition it shows the Total space to be, the remaining space plus the space hidden but in reality it is actually not calculating the hidden space.

Thanks