You might have some issues restoring a backup to a different SDcard due to the size.... even if the new card is the same size.
I had to deal with this with a friends RPi the other night and found that I could shorten the image file using Win DD. I explained what I did in the post http://www.raspberrypi.org/phpBB3/viewt ... 78#p217078
Basically I did:
o Backed up original image with Win32diskimager
o Created a slightly smaller version using Win DD
o Was able to write the new smaller image to a new SDcard without any issues.
Attempts to read directly using the Win DD from the SDCard to disk have not worked or I would simply replace that process with the backup process using Win32diskimager.