see:
How To Trademark a Domain Name: http://www.allbusiness.com/technology/internet-domain-names/...
ICANN Uniform Domain-Name Dispute-Resolution Policy: http://www.icann.org/en/udrp/udrp.htm
If you aren't registering for the purpose of selling to the complainant, it's not bad faith. And it's hard to have bough it to sell to a TM that didn't exist when you registered. You really don't have to tell that much of a story in order to justify your squatting.
See, for instance, (.doc, blame WIPO) http://www.wipo.int/amc/en/domains/decisions/word/2009/d2009...
To win via UDRP, the complainant has to prove: 1) the domain name is confusing, 2) there is no legitimate use of the domain name, and 3) bad faith in use.
UDRP is nice because it is administrative and lawyers typically aren't used. You just file paperwork.
However, with the Anti Cybersquatting Consumer Protection Act (ACPA), bad faith is met by proving bad faith in registration, not in use. That is a much easier standard to prevail on.
ACPA is civil litigation. It has more teeth to it when you win and lose, so lawyers are recommended because you may lose your right to appeal if you don't do things correctly during trial.
Also, remember that trademarks only exist when used to identify goods in the stream of commerce. A person does not acquire a trademark simply by registering a domain name. Therefore, old-gregg may own the trademark if he was the first to use it to identify goods in the stream of commerce.
Side note: if your "squatter" is outside the US, you have to use UDRP because you can't get jurisdiction in VA for ACPA when the person isn't in the US.
I was making the assumptions that 1. the OP wants the name for legitimate business use (not resale), 2. the name isn't already trademarked elsewhere, 3. the name isn't confusingly similar to another legitimate business.
My suggestion was more to incorporate the business, and launch with a similar domain name, trademark everything, and get the business started before trying to take the name from the squatter.