First, you will not have to change your email address in the future, even if you move to a new hosting company or ISP. Second, "www.yourdomain.com" is easier to remember than an extended URL like www.isp.com/client/~yourbusinessname/. Not to mention that a Website with the www.yourdomain.com URL lends more credibility to your organization and usually receives higher ranking on search engines. Finally, if you do not register your domain name now, somebody else could register the name before you. By registering now, you will save money in the long run as resolving domain name disputes can be very expensive, with costs often running into the thousands of dollars. Better to own your domain name now before someone else claims it.