Empire: Total War Installation/ Frustration

Creative Assembly and Sega do have a way of really annoying me when it comes to installing their games. As with the previous installments, Empire doesn't let me install it to and drive other than the C: drive. The problem is, my Crive is full of files that can't be moved or deleted, so I can't install it to the C: drive then move the folders over! The really frustrating thing is that all of the Steam files, and games I have installed from the orange box are all not on the C: drive, so the problem is entirely Sega's. I normally would just return the game, because I don't like it that much, but it was my little brother's birthday presents, so I NEED to get this done for him. Thanks in advance!