I did some seo for several sites and now I have the privilege to do some seo to a brand new site in a niche where I already ranked 1st a site for 5 main keywords. I want to outrank the first site because he screwd me over with the payment. So I bought a niche related older domain and started blasting it. I used all types of backlinks and most of them where high quality. The funny thing is I got this site to PR 3 in like 2 and 1/2 months and its still not ranking good for its keywords- plays around between spots 30-150 in google. The site that ranks first for my keywords is a PR 2 site. Ofourse at first I tought that my site has PR 3 from the old domain but the thing is that the NEW pages I did most backlinks for also have PR 3 (2 pages) 3 PR 2 pages, a lot of PR 1 and 0 pages. So my conclusion with an example is that PR is not really that relevant when looking at competition.