I just bought my wife a new i5 to replace an earlier i5 that is about 5 years old. I would like to house the old C-drive in a box because it has a lot of useful info and I don't want to migrate everything to the new hard drive and fill it up. I want to be able to use the old drive as an external drive. Here is the question: The old drive will have a complete operating system on it using Windows 7. The new computer will have Windows 10. Will the two systems compete with each other. Will having two different systems connected to the same computer create problems?

Thanks in advance for your words of wisdom. I find better info here than most places.