when sourcing links if somethings pr 0 but really on theme is it better than something with a high pr but not quite as relevant?!
Yes, it is more useful if the link is from a related themed site instead from a site which is not related to yours. Over time this pr 0 site will also gain value & pass it on to your site from that link.
actually PR is just nothing if site is serving the purpose. suppose if google.com turns to be pr0.. would ppl stop using G? of course not. pr info was made public by G for giving info on their toolbar used in browsers.. but seo ppl just ruined its purpose and manipulated that number so badly that now G is not serious to give that number accurately to public. So, PR is not important at all. You can check sites strength using various techniques.. like using backlinkwatch.com tool to know if ppl are linking to that site using relevant phrases of that site owner has gathered just bogus links temporarily.
Ginny137, If i had to choose one from the other I would choose the relevant lower PR sites, however in efforts to build a solid linking profile You should build links from all types of different sites.
PR is mainly a grade given by Google to give credentials to a site's quality and popularity. This is mostly used for getting link exchange from other sites, this is at times the basis of how they weigh the value of a link exchange. The higher PR you offer, the better.