PageRank is a highly debated issue for many webmasters. In a nutshell, from my experience PageRank doesn't have much impact on your rankings. To give you an example, I have a website that has a PageRank of 1, but drives thousands of visitors to its pages consistently each month. I have other websites with higher PageRanks that don't generate as much traffic.

The main reason for this is because PageRank doesn't measure your SEO or conversion success. It's a gauge to measure the incoming links to your website and their importance.

I could go on for hours about PageRank and what you can and can't do with it, but I've decided to link out to others who have written extensively on the issue and who have put things much more poetically than I can!

So here's some articles that are well worth reading:-

What Is Google PageRank? A Guide For Searchers & Webmasters
This is Danny Sullivan's extensive article about PageRank and what it is. Well worth a read if you're just starting to find out about PageRank.

Sculpting Your PageRank For Maximum SEO Impact
This is an article by Stephan Spencer about how you can use PageRank sculpting on your website.

Does Google PageRank Factor Into Link Quality? : SEO Book.com 
Here's a great article from Aaron Wall about what he thinks Google takes into consideration when looking at links to your website.