Alot of folks here are concerned about Page rank or 'PR' and myths abound. I think it's important to understand just what this means to a site and more particularly to a Cube Cart site as we are trying to make some money with our efforts.
First of all let's look at PR and what it really means:
One way to look at pagerank is that it is not a measure of relevance, and it never has been. Instead, it's a measure of importance, or material content.
A high page rank site may be more important than other sites, based upon the pages that link to it. But, when it comes to a search on a specific subject, that high pagerank site may be considerably less relevant than pages that are more on topic.
So a search for a fairly generic term is going to end up with search results that have higher page ranks. Because the query isn't that specific, relevance is less important. A search query that is much more specific is likely to bring results that have lower pageranks.
To demonstrate, a search for "food" is likely to end up bringing back sites with high page ranks. A search for "Louisiana Deviled Crab Cakes" (with or without the quotes) is going to result in pages that have a lot lower page rank.
As search terms become more generic, relevance is less a factor, and material content is more of a factor. As search terms become more specific, relevancy becomes more important, and material content is less.
What does this mean to Cube Cart. A PR4 page is a PR4 page no matter what keywords you use to find it. Lot's of sites have higher PR than my sites, but they don't show in my keyword serps because they are not relevant. Use one of several online keyword search tools to see just what keywords are being returned from the major search engines for your keyword term and then adjust your keywords to suit.
For instance on my vitamin site I found that the keyword 'vitamins' returned a serp of about 300 searches while 'vitamin' returned over 4000. Guess what? I changed my keyword to reflect the higher search term and then changed my content to reflect the change.
For a great selection of free online SEO tools, try http://www.webmaster-toolkit.com/keyword-research-tool.shtml
Take this information seriously and adjust your site content for the results. Remember as well that it takes about 6 months for a new site to be ranked and there are no guarantees.
I hope this information is useful and helps you to make alot of money.
