Getting back into this - What all has changed?

So, I've been making slow, automatic money for a while now, and have figured out just what exactly will sell the easiest.

I haven't worked at all on my articles and making sure they sell their products (by staying on good SERP ranks), but I still remember everything I learned from back when I worked on it every day.

So, I decided to try to increase the income to at least a sale a day, which means I'd have to start working my way up to my newer goals.

Problem is, I've been doing my research and it seems that the algorithm has changed sometime between late 2009 and now.

Back then, quality backlinks always assured you at least a good SERP position, depending on how much work you put into getting a good amount of them, but it seems as if backlinks have less bearing on SERP positions than they used to.

I looked and both of my selling articles and both of them are around PR2-4 and have an okay amount of backlinks - more than my competitors, at least.

Still, they're many positions behind, which makes me scratch my head.

I also checked my "control" article, specifically, Angela's Backlinks article by simply searching the word "backlinks", but her article was nowhere to be found.

In order for me to efficiently climb the SERPs now, what do I have to do besides get a good amount of high-quality backlinks for my 2 best-selling articles (on articlesbase.com for now) to get on the front page of their respective SERPs?

EDIT: Then again, maybe I'm wrong. Maybe it hasn't changed that much. There are a lot of factors that could influence this, after all.