The system used the protools on one drive and everything else on another. All protools sessions were stored on the external drive. I did have some issues with it recognizing autotune and amplitube. I tried to work through the problems but my system crashed. Unfortunately we had a severe lightening storm that got through and took out my computer (power supply, mother board, and the video board) I had it rebuilt with a faster processor but went back to the single internal hard drive. My IT guy tells me it makes sense to run the operating system on a separate hard drive from all other software but not to split up the applications as I did. Also, I could never figure out a way to load reason, live, etc, and make them go to anything but the 'c' drive. I guess you could load everything on the 'c' drive and put your operating system on 'D' drive and change the boot sequence to look at the 'D' drive first. I may try this in the future but since the melt down, I only have one drive. I just got the computer back today so I'll let you know if I try the two drive system again. my IT guy recommends the operating system use a 10,000 rpm drive and the other drive can be a 7,200rpm unit.