NOTE: THE FOLLOWING IS MY PERSONAL OPINION, AND IS NOT TO BE CONSIDERED LEGAL ADVICE.
It's important that you address any alleged copyright infringement of your intellectual property as soon as possible.
Waiting too long can weaken your legal basis for your claim.
Secondly, you don't need a lawyer to do this. Laws that are in place protect everyone equally, not just those who can afford a lawyer. Also, keep in mind that two parties are required for a legal dispute. If at any point you don't feel comfortable with where things are going, you can always back down, and you'll be back at square one, having only lost the time that you invested.
Having seen through several similar matters as a web host myself, I would suggest that you contact the other party and inform them that they are using your content without permission, asking them to remove it. Chances are they will cooperate, especially if your initial request is neutral and non-threatening. It's possible that the other party doesn't know that publishing your content without permission is a violation of your intellectual property rights. They may be operating under the assumption that crediting you by name is sufficient to use your content (which may be the case if your content is published under a Creative Commons or similar license). Not everyone has taken the time you have to educate themselves regarding such matters, so it's usually safe to assume good faith, at least initially.
If the other party fails to respond positively to your first request, send another. At this point you'll want to send your communication to them by mail, in addition to e-mail. Get at least a normal delivery confirmation for your letter, but signature confirmation is even better. Even though you'll probably never have to present that confirmation as evidence, the other party will know that you have this evidence, should you need it, which can be a strong deterrent for many.
In your second message, use stronger, but never hostile language. If your tone is too confrontational, your message can easily be interpreted as a threat, which could seriously limit the legal basis of your claim, especially if the other party alleges that you're motivated by greed, vengeance, or another unrelated personal matter, rather than protecting your intellectual property.
You may have (correctly) read or heard that it can be dangerous to threaten someone with a lawsuit, as the other party can sue you first because you threatened them, which can lead to a long and expensive legal battle, which you had no intention of getting involved in.
As I said, it is true that someone can sue you for threatening them with a lawsuit. Someone could sue you for anything as long as they can find a lawyer to represent them and a judge that will hear their case. You can be sued just for posting on this forum. These facts, however, shouldn't concern you, since you know that you haven't done anything to intentionally or recklessly encroach upon another person's rights.
The person who is infringing upon your copyright can try to sue you for protecting your content, however, if they are that stupid you're in luck, because you can probably get a pretty big settlement from them once the case goes before a judge, since they are obviously wrong in using your content without permission, and therefore violated copyright law.
On a side note, the good thing about the legal system is that cases are heard by other human beings, not machines. Human beings can often be completely unreasonable, which is why we have an extensive appeals system at our disposal. This isn't like PayPal closing your account because they didn't like the color of the beach ball you sold in '98. Or your bank charging you a $35 overdraft fee because you exceeded your account balance by $0.01 for the first time in five years, I'm sure you get my point.
To protect yourself legally from being brought to court for this, therefore,
a)verify that your claim is true. Talk to a few lawyer friends, or post a description of your case on forums where such matters are discussed, and
b)never directly threaten the other party, rather insinuate that their posting your content without permission is a violation of the Digitall Millennium Copyright Act of 1998 (Title 17 of US Code, as amended, [cite the exact passage that applies to this violation]). Never mention any lawsuits or anything of that nature, it's enough to let the other party know that they are actionable under a very specific section of the Code.
I doubt that the other party will take the time to verify that what you told them is actually true, but if they do, they'll back down even more quickly. At any rate, this second letter should suffice to get what you want. From my experience, this even works if the law is not 100% on your side, for instance if the particular situation is a gray area, rather than an overt violation.
You have successfully put your opponent on the defensive without exposing yourself legally. If they still choose to ignore you, make use of the full power of the DMCA and send a cease and desist letter to the other party AND THEN to their web host, ONLY in case the other party doesn't respond to this third message (you can find a template for this letter anywhere on the web, it should only take you a few minutes to write it). Under the "DMCA Safe Harbor Provision", service providers are required to remove material that is in violation of copyright law immediately upon you having served them proper notice (the cease and desist letter), in order to NOT be actionable under the DMCA.
In other words, if you tell the other party's web host that the content the user is hosting violates your copyright, they will take it down right away, often without verifying that your claim is true, and OFTEN without disclosing your identity to the offending party. So if you're really worried about the other party counter-suing you, you can go directly to their hosting company, but I wouldn't recommend this, since you'll have exhausted all means to settle the case out of court, if, for some reason, the other party can convince their web host that the content is not a violation of copyright law.
On the same note, I also wouldn't get the party's web hosting company involved in the dispute unless your other efforts fail, even if both parties have the same web host. This can unnecessarily complicate matters, and although Dreamhost or whoever can probably settle the dispute, they may not settle it how you want it to be settled, and you surrender control of the situation as soon as they get involved. If that happens, you may see yoursef(es) in court much sooner than you may have expected.
Let me know how it plays out... good luck.