There is 100MB hidden system space created during Win7 installation. During my consequent (maybe the second, third installation of the system, I found there's only 70MB space left. However, some other's cases showed that their corresponding space could be over 80MB, say 86MB. I guess there's not much differences between these cases. I am using Win7 Pro ver, but I turned my system locale into China, Japan. What I mean is if switching locale may cause the difference of extra space occupation? -------------update--------- Well, I just format the hidden system partition during the GUI Win7 installation (but I set the partition to ACTIVE in DISKPART). Now the Disk Management shows that the hidden system partition has a 72 free space, a 2MB extra space was created. It seems that Win7 could write something into this hidden partition and the added file/info amounts to about 2MB. What are these files?