The first question to be asked is "is your PC capable of running a 64 bit system?" When you have confirmed this:-
Did Acronis back up all of your data in addition to doing a system image and can you see the individual data folders as distinct from a system image?
If they do not appear as separate folders can I suggest that you save all of your data onto the external hard drive (I assume that is where Acronis did the back up), or if not on the cd/flash drive.
Having done this there is no reason for you not being able to transfer it back to your PC when the 64 bit system is installed. I assume you are doing a completely new install, wiping your hard drive totally. I believe that you will need the activation/registration key for the 32 bit system for use with the 64 bit.
If you are in any doubt at all Medion are usually very helpful - one of my pc's is a Medion laptop and they have been very helpful in the past. Here is the link.