Backlink is one of most important seo factors you should focus on it. When SEO was dead, then backlink will be dead. But I think it won't or so far
If your keyword has less than say 50,000 competition on page seo is super important. Otherwise backlinks will play the main role. Yahoo Site Explorer does not show ALL backlinks, less than 50% most of the time. Google Webmaster Tools shows even less. So it is very possible for the #1 sites to have thousands more legit backlinks than what you initially might believe...
Backlinks are not dead, that is probably the main way search engines use to rank websites besides on-page seo.
Backlinks are very important as they are links from other sites to yours. One way links on other sites are the most powerful. Doorway pages are good ways to get your website higher ranking but are less valuable as most doorway pages are links to your site on your own server. You want one way permanent backlinks from websites that are high in PR. http://www.gdiwebsolutions.com