I got a letter from Dominion Associates recently and yes, I was initially afraid. But Unclewulf is absolutely correct: defend yourself. I decided I could sit and do nothing and wait for them to seek a judgement, or I could act.
So I did my homework. I sent them a letter asking them to validate the debt, and waited for them to reply. In the meantime, they did send me a letter asking to set up a payment plan, which I ignored.
The reason I ignored this letter was because, in the course of my research, I found out that open-ended debts (including credit card debts) have a statute of limitations, which varies from state to state. As it turns out, Virginia has a pretty lenient code for consumers, which sets that time as three years from the last date of payment. However, if a consumer makes a payment on the debt, or even acknowledges that they owe it, it will start the clock running from zero and give the debt collector a great position, from which they can seek a judgement. Dominion Associates isn't doing you any favors by trying to "work" with you to set up a payment plan - they want you to be scared, unaware of your rights and willing to make a monthly payment so that you forfeit your right to contest a time-barred debt.
So if you get a letter from these people, make them validate the debt and prove that it is not past the statute of limitations, and do not claim that you owe the debt until it is clear that you have no other recourse. It is even possible that they cannot properly validate the debt, as all I received was a letter from them with the amount owed, the account number, what the debt was for, etc.
Also, treat them as a bill collector, and do not speak with them on the phone. Having done my homework, I will say that there is no reason ever to deal with a debt collector on the phone. They are fishing for you to say something they could use when seeking a judgement - don't provide them with the ammunition. Deal with them via certified mail and if you aren't comfortable with the process get a lawyer to do it for you.
Hope this helps!