Your small business needs a website and therefore needs a domain name. The question then is should you just pick your business name or something else? My suggestion is to obtain two domain names — your business name and also a keyword rich name. A keyword rich name is one that contains words that people are searching for to find your website.
So if you are an electrician for example, you might want ABCElectrical.com and also HoustonElectrician.com. The main website address would be the keyword name but you would direct your company name to it as well so that when you mentioned the name verbally or on a business card, the domain name would be your business name. When someone searches Google for Houston electrician, however, your site would likely be on the first page.