Moving a 7.x library to 3.x , 4.x and even 5.x
runs risks. You might have gotten away with it for now, but do NOT try to move back. Not only has the code (and features) evolved, but those in 7.x allow things the earlier versions did not. Some required database changes to store additional info.
Is the W7 machine 32 Bit
? That limits options.
64bit: Consider booting Linux on a USB drive or fast stick (no mods to the host if it allows a USB boot)