Last year, I had been running the previous version from my hd but decided to run the RT and drums on 2013 from the usb drive. This is one of the install options in setup. I installed the program right over the old on the C drive and pointed it to the usb drive for the RTs/Drums. It freed up lots of space because once I tested it and it worked fine, I then deleted only the RTs/Drums instrument files that were already on my C drive. Works great.