Looking for a tool that would verify integrity of ALL files on a Windows 7 x64 NTFS disk reliably? This is for testing of experimental defrag software, so it really needs to be secure and foolproof. I know it will take a long time, there's millions of files on the disk, but safety just cannot be compromised in a situation like this. Freeware solution much preferred. Can be either Windows software (=inducing pitfalls about files changing due to booting Windows) or a stand alone boot (for example linux boot cd + usb key for storing chksum/metadata).