Laptop HDD swap.

[Caincard]

My gf's mother ran into a snafu  with her .laptops screen dying. I offered to give her a laptop of mine and offered to swap the hdd's so she doesn't lose all her stuff. Now my question is. If i do the hard drive swap. Do i need to do a fresh OS install where the hardware is slightly different (same model don't think they are in the different gen category, just one is slightly newer)?. Her laptop had the OS already on it and didn't come with a disk, and the one i opted to swap with has win 7 pro instead of home.(so i don't exactly want to just transplant her files). Or is there a way i can clone just the OS on each computer and run install them via USB and swap transplant the files?

[BlackMamba]

i'd put all of your important files (and hers) on another hdd and do a fresh install of the os on both pc

[Caincard]

i'd put all of your important files (and hers) on another hdd and do a fresh install of the os on both pc

Already decided on backing  up the files on both computer. My problem with the OS is there isn't a physical media to reinstall from such as a disk or usb. Would i be able to go  throught the recovery partition? though i would think there would be conflict as its not the factory setup it came with.

[BlackMamba]

Already decided on backing  up the files on both computer. My problem with the OS is there isn't a physical media to reinstall from such as a disk or usb. Would i be able to go  throught the recovery partition? though i would think there would be conflict as its not the factory setup it came with.

do you have the recovery cd of windows or the laptop itself? 

[Caincard]

do you have the recovery cd of windows or the laptop itself?

If i remember correctly her laptop didn't have a disk from the factory, and the laptop i am donating doesn't have a disk either.  so i would just be working with the laptops themselves. and i am not sure of my gf's moms willingness to drop money on a new OS. So its a "My hands are tied" situation.