Well if you have a lot of relevant sites linking to you, you should rise. If you have a ton of random sites with no pertinance linking to you, you wont be bumped up.
Updates also boost google ranking.
Page rank (from what I know) is what your site is "worth" on the google search engine. I am not talking about dollars, but by relevance. Google ranking is where you stack up against the competition, and actually appear in the list.
You may have a stellar page ranking but poor Google ranking if everyone else's page ranking is greater than yours. You may have low page ranking but high Google ranking if you have competitors with lower page rankings than you.
I hope this helped
