It is hard to say exactly how much your ranking will rise due to a PR 8 backlink, but it will definitely give you a good boost. The higher the PR that you are linking to the better chances you will have to get a higher ranking.
there's no exact algorithm for your question. getting PR8 backlinks will help. this is all you should have to know.
It depends on how strong or how authoritative that pr8 backlink is. If there is already 100 external links from that pr8 page...forget it. If there is only a few...go for it.
Agree with this one, even a backlink coming from a site with a lot of outbound links doesn't count as much.
the site will only really help you in the rankings if it is relevant although it will still pass along PR either way
If you get back link from a pr 8 web page, your page rank will surely increase. But your Google rankings will depend upon the relevancy of page from where you are getting the link for your website
yea sure you would get a benefit if your site gets a 8 pr backlink but it should be relevant to your site because Google give value to that page only if the profile matches...
i guess about none...it doesn't matter the other website PR for ranking. i got PR1 ) but still on google 1st page