Switching HDD in identical laptops

[Phyrrus]

Hi, guys, i need your help please.
Here is the situation:
I have two nearly identical laptops, one is a HP Elitebook 8440w, the other is 8540w. They are supposedly built using the same hardware components, the only difference is that the 8440w has a bigger display and the graphic card is somewhat different (1gb Nvidia Quadro FX 880 i guess instead of the other one's FX 380 with just 512mb)
Problem: The 8440w has a bigger, 650GB hard drive - windows 8 installed, the 8540w has a smaller one, windows 7 installed. I would like to take out the 650GB/Win8 one and just switch it into the other laptop.
Question: will it boot? I mean I thought that since they are almost identical, I can save myself from the pain of reinstalling windows onthe 8540w, and repopulating the whole system, and just swap HDD's. If it boots, will it be stable?

Thanks a lot in advance for every thought.

 

[hussainali88]

It will boot but you will lose Windows activation !

 

[Phyrrus]

Thanks, Ali, well, i can reactivate windows, still easier than reinstalling all and repopulating all. Thanks for your answer, i will try doing it and come back with feedback if something went wrong.