The UNIX dd command is an incredibly powerful low-level data copy and conversion utility. You can, for example, use it to create disk image copies.

It turns out that there is a version for Microsoft Windows too...

WinDD: Disk Dump for Windows

Its developer has a short but accruate description for it: WinDD - Disk Dump for Windows! Windows XP version of Unix 'dd' command. Safe, effort-free backup for FAT, FAT32, NTFS, ext2, ext3 partition.