In my experience, if the domain is not being used currently and has not been used in the past for anything other then parking and they don't have any trademarks files for it, they have very little argument to say that you stole their name. However, this is not legal advice and shouldn't be taken as such. You always have to be extra careful when your domain is similar to an existing one. It's very easy to file a civil suit in the US even if there is little to no basis for it.
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CEO at InsuranceAgents.com
#24 fastest growing company in US on 2009 Inc 5000 List
I blog about my experience of growing the company at http://www.secondcityceo.com
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