laptop on a 2000 domain and used at home

I just inherited a 2000 server domain at a real estate office and I am fairly new to server admin. (I know enough to get myself in trouble but am studying hard to get up to speed quickly) Several of the agents want to be able to use their home laptops on the office domain as well as at home. I will obvioulsy scan them for viruses andother little beasts before I join them to the domain. My question is this… How do I set the laptops up to be able to access the domain at the office and still be able to access their home network? There may be different set ups at the different agents home locations. PLease be gentle as I said I am a newbie.