Make sure to differentiate between a corporate name filed with a state agency, and a company name used in commerce and/or trademarked. Even if a company has not trademarked it's name or logo with the US Patent & Trademark Office, it may have common law rights in its name that could affect your use of your name if likely to cause customer confusion, etc. It's best to consult legal counsel regarding a planned name or logo before investing time and money into its use.