Everyone who knows anything about trying to get a site ranked in Google or other search engines will tell you the same thing – backlinks are the key! Backlinks are one of the ways search engines can get an idea o how popular your site is. The theory goes that if a lot of people link to your site then it is likely to have something useful and of value on it. If nobody wants to link to you then it's probably because there is not much value on your site.
It is true that Google (more so than other search providers online at the moment) places a great deal of emphasis on links back to your site. It is also true that Google places higher weighting on backlinks that come from sites with a high pagerank. What is not clear is that it also matters about the content and relevancy of the page that the links are coming from.
For example, say your site is about Digital Cameras, well a handy of links from sites that are also about digital cameras, photography, and even other digital devices will have more value than a huge load of links from unrelated sites about toothpaste, or baseball .
This means when you go trying to build backlinks to your site you should stop and consider where you are getting these backlinks from, do not just go willy nilly trying to get links from anywhere, it will work better in the long run to try and get good quality links from sites that are also relevant to your site.
A side benefit of this strategy is that more people are actually likely to follow your links, and you may actually see a fair amount of traffic coming in from your links, which is something that would not happen if you just went out trying to get random links from anywhere.
Remember, relevant, valid good quality backlinks from sites with a high pagerank will get you moving up the SERPs a lot faster than lots of poor quality links. Think about links before you post them and have a strategy!