To be considered a viable web hosting provider you need to have a static IP address. Any other way and you'll have your clients updating their domain records to reflect the new IP constantly. If you're with a colocation provider and they're using DHCP then run....fast! If you're trying to be a web hosting provider off your ISDN or DSL line, do everyone a favor and dont bother. You're not going to have the required resources to host websites on a professional level. If you have clients lined up, you can start small by getting a virtual dedicated server very cheap and as you grow you can move to an actual dedicated server. So the short answer is, if you dont have a static IP and you're going to do webhosting for anyone other than yourself get a static IP, and dont host it off your home connection.