That System Volume Information folder that you can't access is a snapshot of your drive. It is there to protect your data if you have a power failure, your system decides to reboot for no reason, you hit the reset switch without shutting down or you have a nasty crash that corrupts some files on that partation. When you run scandisk on a NTFS volume and it finds a problem with the drive it recalls how the data should be from that image that is stored in the System Volume Information. It also contains a Last Known Good Configuration list so if you ever install a dodgy driver that causes your system to Halt upon boot you can restore to the last known good configuration(contained in that folder).
Think of it as a way of making your data and OS bootup more secure.
[ August 29, 2003: Message edited by: Zombie9920 ]