I disagree with a lot of what has been said here. Yes, original and unique content IS important for SERPs, but what about your visitors? Would you think that adding an informative and relevant article to your blog that your visitors will find interesting a waste of time if it doesnt promote better SERPs? Do not rely on duplicated content for your blog and if you use them do so sparingly, BUT there is nothing wrong with re-publishing content (as long as you have permission) every now and then for the benefit of your readers. Remember, if your visitors like what they see on your site they will be more likely to return. Also, most of your visitors will have no idea whether or not your content is duplicate (ie free use articles). All they will know is whether or not they are interested in it.
A mxture of original and linked content is OK. If someone else has written something you agree with and think is worth repeating, why not use it or link it with their permission.
The times when I run news articles off of other sites etc in my blogs I alway link the article to the original source, but then I add my own take on the subject, usually only a paragraph or so, but my own little spin. If you are just looking to beef up a blog with someone else's work with out rewriting it then you are wasting your time. not only will the seo's not rate you well, but also their will be no personality or continuity in your blog, and no-one is going to be too keen to read through. Just my 2 cents
you shld be going for your own content. . .if u copy some others content then wat is the use of using it . . . . you read the articles by typing the topic which u intend to rite on in some search engines and then write it in your own way. .