I have a minimal system as mentioned above, and I tried using an external USB drive for installation of the whole program, and the RealTracks, etc. There were always glitches, and it was frustrating. I then tried what Peter said, Realtracks and Drums only on external, but it still presented minor problems. I then transferred my photos to the external drive and freed up space on the C drive, and it's a world of difference. It works best for me with everything on the C drive, and I save anything I produce on my external drive.