I hope you don't mind me asking. Can you explain, perhaps in your own words, why other programs and data would interfere in any way with the drive FSX is on? We are always talking about programs and data not being accessed while FSX is running. Technical background.

Now the case for separating the OS drive from FSX one was made and, I think, isn't in question. So I wonder why we should recommend getting at least three drives (OS, FSX, 'others') for a system with limited budget.