Long story: I currently have a small HDD with Windows 7, but I have acquired a brand new HDD along with an edition of Windows 7. However this new edition will expire soon unless I activate it onto a HDD.
So is it okay to use two HDDs with identical Windows 7, and can I easily look through each other's files during a single boot? Or am I forced to restart my computer and choose a boot drive?
The only copy of windows you are using is the one on the boot drive. The other is not being used, it is essentially data. You can access the data on multiple drives using either drive as the boot drive, You don't need windows on both.