Yes.. you can.. but best way to do it.. would be to partition it before you put it in the new Mobo comp.
1. with current comp - partition drive into 2.
2. Change your Mobo/hardware
3. Fire up PC, booting from Windows DVD (or whatever)
4. Install windows fresh on the new partition
This will leave the old windows info in place (except the old MBR will be changed - so the comp will now boot from your new install).
This what you want?.