Quick update.
Turns out the all-in-one is almost impossible to open with breaking it. Since it is brand new, I chose not to break it

I also decided not to use a USB drive (mostly because of the constant noise).
However, I discovered a nice Windows XP feature, that is there since the beginning (so almost 10 years!!!), but that I never knew existed until last week:
Dynamic Disks and Spanned Volumes.
Now I have one big 6Tb volume from which I backup only the important data (music and pics mostly).
It's still not as quick as I would like it to be in MM, but I can live with it for now.
Quick update.
Turns out the all-in-one is almost impossible to open with breaking it. Since it is brand new, I chose not to break it :)
I also decided not to use a USB drive (mostly because of the constant noise).
However, I discovered a nice Windows XP feature, that is there since the beginning (so almost 10 years!!!), but that I never knew existed until last week:
Dynamic Disks and Spanned Volumes.
Now I have one big 6Tb volume from which I backup only the important data (music and pics mostly).
It's still not as quick as I would like it to be in MM, but I can live with it for now.