We've mentioned duplicate content issues several times already. It takes a multilayered approach to avoid the issue completely.
The first thing you need to do is write your own content. That cash advance article you wrote needs to be your own. Those emails we all get about "free articles" for your site just won't do. They get posted on tons of sites. So even if they're well written and cash advance related, skip them.
You should also keep an eye out for other sites scraping your content. Search engine spammers create dozens if not hundreds of sites per day, each with many pages. As you can imagine, they just don't have time to write their own web copy. They have programs that go out and find content for them. Eventually, they'll find your site and grab your property. This can hurt your rankings in the search engines. If you find a site that's grabbed your content, send them an email asking them to take it down. That works in the majority of cases.
As far as your site goes, you want to make sure that a given bit of content is only accessible by one URL. So your cash advance article should be at http://www.example.com/cash-advance.php and only that URL. This blog isn't great about that. There are about 3 different ways to get to the same content: this main page, the individual post page, and then the archive pages. You should try to avoid this when designing your own site. If your site is purely static pages, this isn't hard. Just make sure your article is only on that one page. It's a little more difficult on dynamic sites. If you're pulling articles from a database based on the URL, make sure you do some validation to ensure that your content is accessible only via one URL. We recently had an issue where /page.php/page.php was pulling up the same content as /page.php. We added some code to check for multiple slashes in the url and 301 redirected all of the offending URLs to the home page. Problem solved.
Dynamic pages also sometimes have query strings appended to the end of the URL – all of those pages that have URLs like page.php?blahblahblah. This may or may not cause an issue, but I'm of the mind that you shouldn't leave it up to the search engines if you can avoid it. Unfortunately, I haven't come up with a solution I like for this yet. If your cash advance article is at cash-advance.php, then cash-advance.php?blah is going to pull up the same article. You could add some code into each PHP page to check for things in the query string (they get put into $_GET), but that can be a pain if your site is already built. It should be possible to redirect all requests that have a query string via mod_rewrite, but I haven't figured out how yet. Once I figure it out, I'll let you know.
Jon K.