Getting high pr sites to rank to you is not as important as the quality of the link. I wrote an article a few months ago and this is one location that is is published on the web. When it first got its page it was a pr0 and now it is a pr3. So my pr0 link is now a pr3, just takes some time. here is a link to it
Without a Throne of Links-King Content Has Nowhere to Sit in the SEO Kingdom
Now , the beauty of articles is in the format of the article. Links are assigned value buy about 100 different factors. Having your key word or words in the title, content and placement of the link on the page are a few. The number 1 reason i suggest articles is that you controll the title of the page, most places that publish an article use the title of the articl as the title of the page. Notice that my keywords are in the title, the keywords are also in the content and in the resource box.
Most people think it has to be from a related site but value comes from the page, not the site that the link is on and the pr of the page, if this were not true then there would not be a PR assigned to all indexed pages, not the pr of the index page if your link is on another page.
I would suggest a stable and consistent article marketing campaign, and i would submit to as many directories as you can, the internet is all math, a numbers game.
You can get filthy rich on the net if you actualy think things through and use some common sense.