Help moving users and computers in domain?

Hello,
I did some research online, but wanted to get opinions on here as well. I work for a company doing some moving around. We have 4 stores, each store has a domain controller. It???s a single forest multi domain setup. We are getting ready to move all of the pc???s and users from store A over to store B. Do I need to take them off the A domain, and then when I physically get there pc???s up and going at store B, just add them as new users in the B domain? Or is it as easy as moving the user and computer from within active directory from store A to store B? If so, does it matter when I do move them in active directory? For example would it matter if I physically move the computer first, and then after firing it up at store B, I then move the user and computer in active directory? Its my first move and figured I would get a little help. Thanks in advance???