I'd be happy with two hard drives. One drive... the c drive will be the main disc that holds windows, and any programs you install. You could use the second hard drive to store your data. And should anything happen to your main drive your data will be relatively safe on the second drive. Another strategy you could use is to backup your c drive to the second hard drive using something like Acronis True image. The permutations of using separate drives are endless, depending on what you use your pc for. I have 3 drives in my pc. I use one for storing photos and the other one for backing up. It's certainly no disadvantage having two drives instead of one. I'm sure others here will have different ideas, but I'd accept the two drive set up myself.