You can use winimage, to copy a partition or the entire disk. To restore it requires the same SD size and also the same hardware.
Personally I would probably use ROM Manager and Titanium backup. The advantage with titanium is if you go from one Android device to another and/or a different SD card since Titanium backups the app and the app data, not the exact image partition.
If you want to backup the image partition you can use ROM manager and you can create a snapshot of you configuration.
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