by ear » Fri Apr 01, 2011 4:16 am
First, "trademark" is not a verb, so you cannot "trademark" something. It is a noun or an adjective. You may obtain a trademark by using it on your goods and services in commerce (in the USA). You may also file a state and federal application for registration of your trademark. The only way to know "they haven't trademarked it" is if you know that they have never done any business using that name on their goods or services.
A domain name (by itself) is not a trademark any more than a phone number or address, but can obtain the status of trademark after it acquires "secondary meaning" associated with your goods or services.
If you have started using the trademark earlier than the people who own the similar-looking domain name, you may want to take a look at the laws on "cyber-squatting". If they registered a domain name and you want to buy it from them, then you should negotiate in good faith.