I found out about 6 months ago that a company on the West Coast was using my company name: Green Homes Carpet Cleaning. Actually they use two variants of my name, one which drops the S, and another that has "and Restoration" tacked on the end.
They were coming up in my searches for myself on search engines alongside my company. A local person searching for me might find them and be put off. This West Coast company is a standard non-green steam cleaner also. I did not like this situation. Research showed that they first came on the web 10 months after I did.
So.... the moral is that I paid the fees to register my company name with the federal trademark registry. Expensive, but I think I did the right thing. If the name intereferenc gets any worse, I can now send them a "cease and desist" letter and inform them that they must stop using my name.
If you are serious about your business, consider registering your company name with the federal government. Don't bother with state registrations. The federal registration alway trumps them in court.